I love my Nextcloud instance, too. Zero problems in the past 4 years. I don’t run many extensions on it, though. The mobile app works great as well.
Trillium plus its sync server in a VM is my goto for notes. Mobile isn’t a problem (I usually drops everything into my notes app, then expand on it when I’m in front of a full keyboard at home).
Not sure how I could get through my day without either of these two.
It works on up to 5 devices at the same time. I’ve used signal on my phone, with it also open on my computer with zero problems. Syncing is instantaneous.