greenstumps
I'm just going to reply so you know you are not alone in the darkness hoping for the light of a decent small form factor and UI ...
but firstly, I just emphasise that I know this problem is coming from Google and we cannot expect GOS devs to work around Google $hitine$$ or put their resources into a phone that doesn't meet their criteria. The GOS account comment above is really helpful because now I understand why moving GOS on Pixel 5 to Android 15 is not only 'not easy' but also a pointless exercise and waste of resources despite the same SD765G/X52 modem as the 5a.
As a Pixel 5 owner, I'm still feeling really raw and angry that Google move the cheaper 5a to 15 but not the flagship 5, despite the same chipset/modem. I just try to remind myself that it is access to Android 15 that Google are denying us and that GOS/Android14 is still a plus over the original Android 11.
That really just leaves the discussion points to be over the issues you raise about form factor & materials, weight, battery life and 'why we can't have nice things'. And boy, can I talk about this in an echo chamber ... :) I almost want to start a new 'off-topic' thread.
Google are not getting an upgrade purchase from me until they sell something small that doesn't weigh almost a quarter of a kilo once it is in a flip case. The upcoming Pixel 9 is not looking hopeful either. I purchased my Pixel 5 direct from Google, still at a flagship/premium price point but with a trivial discount, in late Autumn 2021.
It was only the sweet spot of GOS (with Android's more recent SElinux implementation) + SD765G power efficiency + Pixel 5 form factor that finally brought me into the Android ecosystem. I admit that modern life had started to become increasingly difficult without travel apps on my Blackberry OS Q10. I'm lucky to have dual sims with the same number; so GOS/Pixel 5 is my banking/travelapp/away from home phone and the Q10 remains the daily driver. The Q10: small, week+ battery life, screen turns on when I open the flip case, email just a swipe away and other UI stuff that is still streets ahead of the Android launcher even after 10+ years.
I'll stop here for now, maybe we should have an 'off-topic' thread after all. My original intention in replying had just been to let you know you are not alone alone in the darkness of the world's $hitification with giant, heavy phones, poor battery life and hopeless UI.