You can buy a Linux phone today and make sure the vendors get their food on the table. Software is getting better. If you choose a phone with mainline kernel support (e.g. one that can run Mobian or PureOS), you can literally watch your OS improve month after month.
Alternatively, you can support the user-space ecosystem directly and fund the developers who make it happen. Donate to Sebastian Krzyszkowiak [0] and Guido Günther [1] if you can!