@Archivist remind supports all that kind of stuff but its CLI-only.

you can do silly shit like targetting a date and moving forward/back a week (used or "last thursday of every month" rules) or expressions (every 13th but only if also friday) and there's an "omit" stack to ban certain dates from scheduling and push events before/after.

it is the god-tier of recurrence schematics but since its cli-only you have to pile on more scripts to get that in to ical.

i've just been musing about abusing it to output todo.txt instead.

emacs diary mode does something similar but not as extensively.