Buy an unlocked bootloader phone (ie oneplus) and put lineage os on it. Lineage doesn't come with any of the google apps or the play store, just a few basic apps and the ability to put whatever else you want on it.
This is what I've been doing for a few years now. Some apps require Google Play Services (Revolut?), some show a warning that can be ignored and run fine afterwards (Authy, Signal), some have limited functionality like no notifications (Slack), but many work just fine (Firefox, Spotify, and even Messenger Lite)