Get a XiaoMi, unlock it, install LineagoOS, do not install Google apps ("gapps"), use microG if you absolutely need to use apps dependent on Google services but

Get a XiaoMi, unlock it, install LineagoOS, do not install Google apps ("gapps"), use microG if you absolutely need to use apps dependent on Google services but try to use them first without, many work fine even though they insist on needing Google services. Just like all other phones you'll still have the proprietary radio firmware running on your device which could try to snoop on you. If you want to avoid this risk either get one of the "Linux phones" with discrete radio hardware (not integrated into the SoC, only connected through a serial line, no access to main memory or storage) or get a dumb phone with a removable battery.