Screw M.2, I want to use my enterprise grade 7TB U.2 Kioxia drive in my 50 bucks Chinese phone, I just can't live without it!

SD cards and M.2 drives are not really comparable, since they are used for different things. It would be cool to have a phone that has main storage a M.2 drive, but i would still want it to have an SD card slot.

M.2 would make phones inordinately thick and un-usable. If you really need more than 1TB of storage on your phone, dump your pictures and Videos every so often to a home NAS PC running TrueNAS Core or Scale. And if you have Music on your phone that you own the files to, consider using your home NAS as a Media Server using Plex and use Plex Amp or some other app to stream the music direct to your phone.

The performance would be wasted on android since file access has gotten so damn slow on recent versions. It would be awesome on a Linux phone though.