Tal, thank you updating and submitting your patch. It fills a real hole in Idle customization. I am already using it to tweek the completion popup delay to find the best value for me.
I opened these followup issues.
#22703 fix the behavior of Options / Code Context
#22704 rethink 'enable_xyz' system and use consistently
#22705 add 'option-help' option for doc and entry checking
#22706 write [x] and [x_config...] sections together in user .cfg
#22707 makes changes take effect immediately or indicate if not
I will later review this issue to see if I missed anything else.
I am leaving this open until I add a user-oriented news item and edit the Idle doc.