DeGoogle Yourself

is this a rant or are you looking for actionable info? if it's the latter, you need to determine which version you got exactly. Xiaomi ships different versions under the same name. like, they start off with Snapdragon SoC, then swap in Mediatek, then maybe slip in previous gen Snapdragons with only 4G/no NFC, etc.

you also didn't specify if you've already unlocked the bootloader, which is an (at least) week-long process.

your best bet would be to get rid of that phone, then go to LineageOS devices page, use the Filter to filter for current version (i.e. 22 at the moment) and then look for used devices you can get at cheaply. e.g. although it's a 5-year old model, the Poco F1 is an almost ideal hacker phone - fast SoC (faster than the one you got), available with 8 GB RAM, has the widest OS support (including PostmarketOS), it's not glued shut so you can swap the battery, etc.

edit: forgot to mention, you want a device that has official LineageOS support. that's not the only way to get a non-google-infested phone, but then you're dependent on some rando from XDA to ship you updates when they get around to it.