

just recently (2 months ago), I bought a Moto G84 5G, specifically because it had a snapdragon processor (and therefore good custom ROM support), is officially supported by LineageOS and it was cheap (160 EUR). I never needed a flagship phone, the cheap phones ~200 EUR always worked fine for me.
I was using Xiaomi/Redmi/Poco devices before that, but it seems that they have gone entirely Mediatek in that price segment, which is a shame.
I don’t have any anecdotes, really. On all my cheap devices, I never really had any issues with apps getting killed by battery management. I know that sometimes, you’ll have to specifically switch off battery management for these specific apps, which can usually be done with a single action that the app generally let’s you access directly on first setup.
But I’ve always used stock android or at least AOSP based Roms - I’ve never stuck with OEM Roms longer than the (usually) first 7 days they keep you from unlocking the bootloader. Once I can unlock the bootloader, the OEM Rom is gone.
I do know that some OEMs have their own battery management implemented on top of androids, which is often more aggressive, and a bit more convoluted to access.