Do you still have your Poco X3 Pro, or am I confusing you for somebody else?
I have mine and in addition to different flavours of Android it can also run Sailfish and Ubuntu Touch with Halium/Hybris compatibility layer — they both still require some Android firmware to be installed as they use some low-level Android services co communicate with certain hardware, but otherwise both work natively. Battery life is significantly shorter — by that I mean it's nothing compared to that: https://breloma.m0xee.net/notice/AaMNrF7DumoWqX6Z8a
But both can easily last through a day even being actively used.
There's even a Debian variant based on Hybris — Droidian, it also mostly works. There are a few rough edges here and there, but you can make voice calls and use mobile data without any issues, and you can use "mainstream" Phosh UI with it.
In Sailfish and Ubuntu touch even cameras work and you can even shoot videos — it's nothing exceptional as they don't have advanced post-processing that Android camera apps have, but there is nothing bad about them either, for most cases they'd be sufficient.
And if any need for Android apps arises — it can easily be done with F-Droid. I didn't test those nasty banking apps, but everything I've thrown at it worked perfectly — Firefox Mobile and Element, complete with video calls.
Having something like postmarket OS would be even better, but mainline kernels don't work on it, for that you can get old Poco F1 — it's hardware shows its age already, but it's actually usable with PMOS: https://drewdevault.com/2022/08/25/pmOS-on-xiaomi-poco-f1.html