The spotify issue i have is that I can see the currently playing song and pause/play (with a slight delay) but skipping to the next or previous song doesn’t always work for me. I attribute this to using a free spotify account given the other inconsistent behaviors I have with spotify.
Notifications on the pinetime work as a queue, if there are 5 notifications it will clear the oldest when a new notification come in. My understanding is the queue size is a memory limitation that might increase as development goes on but for now they want to keep as much memory free for new features.
for the group texts its nothing, I will know its group text because my phone will vibrate but my wrist will not. Other notifications like from discord or emails work without issue. it is a bit annoying that group texts do not work as my family mostly talks in group texts. Another down side to the notifications is that they do not display a timestamp and even though the notification title will scroll the text within the notification will not.
The navigation thing is interesting as I recently had to disable OSMand notification in gadgetbridge because i found if you are driving and navigating with OSMand, then take a wrong turn that you will get spammed with OSMand notifications on the watch while it is trying to re-navigate. I can try playing around with it this week but based on that link it sounds like it is still a work in progress.