If you don’t need the GPIO then buy a small form factor office PC like a Dell Optiplex Micro or a Lenovo/HP equivalent. They cost about the same on the used market, are more performant without the ARM headache and use only marginally more power (maybe 5-10w more at idle).
As of the latest release (21), you can simply install microG on regular LOS and no longer need to install LineageOS for microG since it now includes the necessary signature spoofing support.