Other than your carrier give it for free or cheap, I don’t really see the reason why should you buy new phone. I’ve been using Redmi Note 9 for past 3 years and recently got my had on Poco F5. I don’t see the point of my ‘upgrade’. I sold it and come back to my Note 9. Gaming? Most of them are p2w or microtransaction garbage or just gimped version of its PC/Console counterpart. I mean, $400 still get you PS4, TV and Switch if you don’t mind buying used. At least here where I live. Storage? Dude, newer phone wont even let you have SD Card. Features? Well, all I see is newer phones take more features than it adds. Headphone jack, more ads, and repairability are to name a few. Battery? Just replace them. However, my Note 9 still get through day with one 80% charge in the dawn. Which takes 1 hour.
I am genuinely curious why newer phone always selling like hot cakes. Since there’s virtually no difference between 4gb of RAM and 12gb of RAM, or 12mp camera and 100mp camera on phone.
Have you thought about flashing a custom rom on your phone, or getting a phone that supports custom roms if you don’t have one already?
I have an old samsung galaxy s5 still running LineageOS and while a little slow it’s still usable as a backup in case my current phone shits the bed.
The process is fairly straightforward, and if you’ve installed linux on a laptop you can install LOS on a phone.