Posteo, 1 Euro/month since many years. https://posteo.de/ Germany based, and you can even pay with cash. I noticed Proton does not allow email forwarding with the free plan. With Posteo you should be able to use pop3 (not possible with Proton free plan I think) and fetch your inbox content if you like.

Thanks. Requires root though. https://f-droid.org/en/packages/dev.ukanth.ufirewall

Besides having a go at removing apps you can install NetGuard https://f-droid.org/packages/eu.faircode.netguard and then block all apps including system apps from using network. From there allow only the apps like Signal you want to give network access to. Drawback is that NetGuard needs an internal VPN connection to work so you can’t use a VPN services and NetGuard at the same time.

Friendica is an alternative for Facebook. https://friendi.ca/ There’s an Android app for it : https://f-droid.org/en/packages/com.livefast.eattrash.raccoonforfriendica

With /e/os you will also have microG. And /e/os has a new installer which can make flashing much easier. https://doc.e.foundation/devices

Did you try CachyOS ? https://cachyos.org/ I’m impressed by how snappy it is on older computers.

Bold :-) openSUSE is based on zypper and rpm. Arch Linux uses its own package system.

p.s. Please replace that Change my mind guy with a Calvin and Hobbes one.