Look into installing a custom ROM, some phones are not supported but many are by at least one custom ROM. I personally installed GrapheneOS and recommend that or calyxOS (never used it but hear good things) but those are only available for pixels, iirc LineageOS has the widest support but also isn’t quite as secure. F-droid and Aurora store for apps.
OnePlus phones are rootable if you buy them unlocked (not from a carrier), and you can install anything you want on them. Some of their older phones even support straight up Linux mobile.
Look into installing a custom ROM, some phones are not supported but many are by at least one custom ROM. I personally installed GrapheneOS and recommend that or calyxOS (never used it but hear good things) but those are only available for pixels, iirc LineageOS has the widest support but also isn’t quite as secure. F-droid and Aurora store for apps.
OnePlus phones are rootable if you buy them unlocked (not from a carrier), and you can install anything you want on them. Some of their older phones even support straight up Linux mobile.