Can I buy a pure Android device?

[busslina]

I mean a device with comes with pure Android, without any manufacturer customization in order to have a predictable behaviour and achieve my goal of have my foreground service running forever without any battery optimization.

A second question would be if I can do the same on any mobile phone, by flashing it with a pure Android image.

(I don't know even if there exists such a think called Pure Android Image)

Thank you