I try it regularly and I was running an org-mode based task management for a year and some months in between, but man, I do not have time and patience for sync conflicts in 2025. It can work but I have to be very cautious, and iCloud sync being a bit mysterious does not help.
But I've also recognized that I don't have very complex projects, that GTD tools do not matter since their contents are transient by nature and that Apple Reminders is basically good enough. As a bonus it allows me to share Lists/Projects with my wife.
I totally understand this situation. I actually never had a good mobile set up when I was on iOS and only when switching to Android was able to finally setup something I liked using orgzly-revived, syncthing, and android Emacs.
As for GTD, I never did proper GTD until about a year ago, after reading the GTD book. I don't consider my life complex by any means, but I've been surprised at the amount of projects in my life that have been reified in my system.
I am practicing GTD since ~15 years already, but while I stick to some practices (review, inbox and so on), I have a simpler setup for projects and files, sufficient for my needs. One of the lessons is that GTD and productivity systems are not about tools - I am equally productive (or unproductive) in emacs, omnifocus, reminders. The advantage of OF and reminders is that I don't have to look after sync, workflow-wise I quickly learn to navigate around idiosyncrasies of each of them and settle on the same workflow, helping myself with scripts and glue code where I need it.
This said, I still keep my long-term notes in denote, because it works and I don't trust Apple Notes for long-term stuff (missing built-in export).
