Tried it out a while ago, and found that I prefer GNOME's UX and configurable shortcuts better, and that two side-by-side applications on my laptop is the most "tiles" I would realistically want.
I don't watch a lot of youtube, but DuckDuckGo browser (on Android and Windows, at least) has a Duck Player that removes all of the cruft around videos and is private afaik.
Fossify Messages and QKSMS/QUIK (unmaintained but has worked well for years)
I was interested in these "light" phones for a bit, but they seem a bit gimmicky and expensive. I understand not having a browser on purpose, but for communication, none of them (AFAIK) support Matrix or even XMPP (even some old feature phones had a Java Jabber client). Punkt MP02 supports Signal though.
Android phone with custom ROM (Lineage, /e/, Graphene, DivestOS...) is a possibility, and would be usable until hardware is incompatible with the phone/wifi networks.
If you have a patience of a saint, PinePhone and Librem5 are Linux phones, both in fairly early stages.
Tried it on an older Pixel with GrapheneOS.
Can't zoom, can't switch to wide-angle lens. Camera does not balance brightness by the focus point. Otherwise pictures look pretty much the same.
I suppose this was made for specific devices in mind?