Thanks Afmob for pointing out a flaw in my re-work, hope it's now right after adding a couple of sub-steps at the start of step 10.
Prelims
a) R12C3 = {19/28/37/46}, no 5
b) R1C45 = {69/78}
c) R1C67 = {13}
d) R23C8 = {19/28/37/46}, no 5
e) R3C12 = {29/38/47/56}, no 1
f) R45C1 = {15/24}
g) R5C78 = {18/27/36/45}, no 9
h) R67C1 = {13}
i) 14(2) cage at R6C7 = {59/68}
j) R78C5 = {19/28/37/46}, no 5
k) R8C23 = {15/24}
l) 11(3) cage at R1C8 = {128/137/146/236/245}, no 9
m) 20(3) cage at R5C2 = {389/479/569/578}, no 1,2
n) 21(3) cage at R8C1 = {489/579/678}, no 1,2,3
o) 29(4) cage at R2C6 = {5789}
p) 18(5) cage at R2C4 = {12348/12357/12456}, no 9
Steps resulting from the Prelims
1a. Naked pair {13} in R1C67, locked for R1, clean-up: no 7,9 in R2C3
1b. Naked pair {13} in R67C1, locked for C1, clean-up: no 8 in R3C2, no 5 in R45C1
1c. Naked pair {24} in R45C1, locked for C1 and N4, clean-up: no 7,9 in R3C2
2. 45 rule on N1 1 innie R3C3 = 1, clean-up: no 9 in R1C3, no 9 in R2C8, no 5 in R8C2
2a. 18(5) cage at R2C4 = {12348/12357/12456}, 2 locked for C4 and N2
2b. 2,4 of {12348/12456} must be in R23C4 -> no 6,8 in R23C4
3. 45 rule on N2 4 innies R12C6 + R23C4 = 14 = {1238/1247/2345}, no 9
3a. 5,7 of {1247/2345} must be in R2C6 -> no 5,7 in R23C4
3b. 29(4) cage at R2C6 = {5789}, 9 locked for C7, clean-up: no 5 in R7C6
4. 1 in N4 only in R6C12, locked for R6
4a. 45 rule on N14 2 innies R6C12 = 2 outies R23C4 + 2
4b. R23C4 contains 2 = {23/24} = 5,6 -> R6C12 = 7,8 contains 1 = {16/17} -> R6C1 = 1, R6C2 = {67}, R7C1 = 3, clean-up: no 7 in R8C5
4c. 9 in N4 only in 20(3) cage at R5C2 = {389/569}, no 7
5. 45 rule on N3 3(1+2) outies R12C6 + R4C7 = 1 innie R3C9 + 9
5a. Min R12C6 + R4C7 = 1{57} = 13 -> min R3C9 = 4
6. 11(3) cage at R1C8 = {128/146/236/245} (cannot be {137} because 1,3 only in R2C9), no 7
6a. Min R1C89 = 6 -> max R2C9 = 5
7. 45 rule on N7 2 outies R6C2 + R7C4 = 1 remaining innie R9C3 + 5
7a. Max R6C2 + R7C4 = 14, min R6C2 = 6 -> max R7C4 = 8
7b. R6C2 + R7C4 cannot total 9 -> no 4 in R9C3
8. 45 rule on N78 3 remaining innies R789C6 = 1 outie R6C2 + 5
8a. Max R6C2 = 7 -> max R789C6 = 12, min R7C6 = 6 -> max R89C6 = 6, no 6,7,8,9 in R89C6
8b. R6C2 = {67} -> R789C6 = 11,12 = {128/146/236/129/156/246} (cannot be {138} which clashes with R1C6, cannot be {245/345} because R7C6 only contains 6,8,9)
[First time through I accidentally omitted one of the combinations for R789C6. I’ve had to do some re-work but have kept to my original steps as much as possible.]
9. 45 rule on C6789 4 innies R3456C6 = 25 = {1789/3589/3679/4579/4678} (cannot be {2689} which clashes with R7C6), no 2
9a. 2 in C6 only in R89C6, locked for N8, clean-up: no 8 in R78C5
9b. R789C6 (step 8b) contains 2 = {128/236/129/246}, no 5
9c. R12C6 + R23C4 (step 3) = {1238/1247/2345}
9d. R3456C6 = {1789/3589/3679/4579/4678} -> R12789C6 = {12359/12368/12467/23456} (cannot be {12458} because R12C6 + R23C4 only contains one of 1,5)
9e. 6 of {12368} must be in R7C6 -> no 8 in R7C6, clean-up: no 6 in R6C7
9f. Naked quad {5789} in R2346C7, locked for C7, 7 also locked for 29(4) cage at R2C6, no 7 in R2C6, clean-up: no 1,2,4 in R5C8
9g. R12C6 + R23C4 (step 3) = {1238/2345}, 3 locked for N2
10. 29(4) cage at R2C6 and 14(2) cage at R6C7, R2346C7 = {5789} = 29 -> R27C6 = 14
10a. 45 rule on C6 using R3456C6 = 25 (step 9), R27C6 = 14, 3 remaining innies R189C6 = 6 = {123}, locked for C6
10b. Max R7C7 + R8C6 = 9 and 12(3) cage cannot be [363] -> no 2,3 in R6C8
11. 45 rule on R789 4 remaining outies R6C2789 = 23 = {2579/2678/3569/3578/4568} (cannot be {2489} because R6C2 only contains 6,7, cannot be {3479} because R6C7 only contains 5,8)
11a. Min R6C278 = 15 -> max R6C9 = 8
11b. 2,3 of {2579/2678/3569/3578} must be in R6C9, 6 of {4568} must be in R6C2 -> no 6,7 in R6C9
12. R12C6 + R23C4 (step 9g) = {1238/2345} -> R12C6 = [18/35] -> R1234C7 = 1{789}/3{579}
12a. 45 rule on N3 4 innies R123C7 + R3C9 = 24 = 1{89}6/3{579} (cannot be 3{89}4/3{78}6 because R1234C7 only contain one of 3,8), no 4,8 in R3C9, 9 locked for N3, clean-up: no 1 in R2C8
13. R12C6 = [18/35], R123C7 + R3C9 (step 12a) = 1{89}6/3{579}
13a. Consider placements for 5 in R3
5 in R3C12 = {56}, locked for R3 => R123C7 + R3C9 = 3{579}
or 5 in 16(3) cage at R2C2, locked for N2 => R12C6 = [18] => R123C7 + R3C9 = 3{579}
or 5 in R3C79 => R123C7 + R3C9 = 3{579}
-> R123C7 + R3C9 = 3{579} -> R1C7 = 3, R23C7 + R3C9 = {579}, locked for N3, R12C6 = [18], clean-up: no 2 in R1C3, no 7 in R1C45, no 2 in R3C8, no 6 in R5C8
13b. Naked pair {69} in R1C45, locked for R1 and N2, clean-up: no 4 in R2C3
13c. R2C9 = 1 (hidden single in N3) -> R1C89 = 10 = {28}, locked for R1 and N3, clean-up: no 2 in R2C3
13d. Naked pair {46} in R23C8, locked for C8,
13e. Naked triple {457} in R1C123, locked for N1, clean-up: no 6 in R3C12
14. R23C4 = {23} (hidden pair in N2), 3 locked for C4
14a. 18(5) cage at R2C4 = {12357} (only remaining combination) -> R4C23 = {57}, locked for R4 and N4 -> R4C7 = 9, R6C2 = 6
14b. Naked pair {57} in R23C7, locked for C7 and N3 -> R3C9 = 9, R3C1 = 8, R6C7 = 8 -> R7C6 = 6, R4C6 = 4, R45C1 = [24], clean-up: no 2 in R3C2, no 1 in R5C7, no 5 in R5C8, no 4 in R78C5
14c. Naked pair {23} in R89C6, locked for N8, clean-up: no 7 in R7C5
14d. Naked pair {19} in R78C5, locked for C5 and N8 -> R1C45 = [96]
15. Naked triple {579} in R56C6 + R6C4, locked for N5, R6C5 = 2 (cage sum)
15a. Naked pair {57} in R6C48, locked for R6 -> R6C6 = 9, R6C3 = 3, R2C3 = 6 -> R1C3 = 4, clean-up: no 2 in R8C2
15b. 6 in N7 only in 21(3) cage at R8C1 = {678} -> R9C2 = 8, R89C1 = {67}, 7 locked for C1 and N7
16. 25(4) cage at R8C4 = {4579} (only remaining combination) -> R9C3 = 9, R7C4 = 8 (hidden single in N8)
17. 45 rule on R6789 1 remaining innie R6C4 = 7
17a. R6C8 = 5 -> R7C7 + R8C6 = 7 = [43]
and the rest is naked singles.