LineageOS without gapps is really usable if you set aside the "big" social media apps. WhatsApp can be sourced from their website as an APK. The social apps like facebook, instagram, snap, tiktok and others all require Google Play's tracking services (aka gapps).
For YouTube there's multiple better alternative open source apps available, and mastodon, amethyst and the fediverse apps on f-droid are far superior in terms of performance to the Google Store alternatives.
I have a Fairphone and i get updates pretty frequently so not sure what you mean?
That Fairphone has 13 just tells me they don't waste employee time in their small business on useless upgrades just for the sake of it. Their point is fair wages and ethical mineral mining: better that they have a workable phone without even more fluff, it seems to be tricky enough already in this world :(