Some good news
It seems that the same mod as in the last update for the WM1 firmware is also possible on the A50.
The WM1 update:
https://www.head-fi.org/threads/sony-walkman-os-custom-firmware-non-android.943661/post-16123520
For now it will come only for the A50 FE version (the stock based one) as the A50R FE mod needs some attention regarding some issues that some users are encountering with the "An error has occurred" message.
I won't give an ETA, but it should come soon.
First, will come the ZX300 update, of course. (patience is a virtue

).
Edit: it may also work on the A30/A40 players, but that will take more time.