You could use the arm64-a GSI image for the M20.
A GSI image is not a phone specific image, it can be used for many phones that support this system.
It can be that everything works great, but it can also be that some things do not work as they should.
On my Xiaomi Redmi Note 9pro, the fingerprint sensor goes crazy, and the reception strength is not displayed in the car, even though there is reception on the phone.
I had noticed that so far. It could be that this is not the case with the M20, or something else.
But it’s worth a try in any case, better than with the crappy Google on the phone.
Here is an installation instruction from the Redmi Note 9pro, should possibly work for you. GSI Installation on Redmi Note 9pro with Super Partition and root
Here you can find the latest images: https://android.l1nux.org/index.php/s/tNyG9ZcrjGBPrdH
You need the …arm64_avS.img.xz file.