I tried that, too. I already had a Debian VM on my phone years ago. Along with some VNC software and an android app to connect to the virtual desktop. It was really cumbersome to use. Especially keeping it open in the background and using it while doing other things was next to impossible.
Samsung ships a traditional desktop environment on their phones and tablets since years. Phones need to be pluggeg into a USB-C dock, tablets need a type cover. Others followed them with similar environments. Surely this is not meant for touch-only use.
I know. And that seems to be quite well made. Unfortunately they don’t have HDMI output on their mid range devices. At least the Samsung phone of my wife doesn’t output anything when connected to the TV. And we both refuse to spend $1.000 on a phone. And I mean this convergence is kind of a strange use-case. On my desktop I have a computer attached to the screen anyways. KDEconnect syncs everything and I don’t need to attach my phone. And on the go, I don’t have a keyboard and monitor with me. I think convergence is useful if you want some private stuff on the second monitor at work. Or while sitting in the computer science lab at school/uni and those machines are locked down. It’s a bummer only/mainly Samsung does that. And the situation with HDMI and that USB alternate mode and the manufacturers using that to distinguish their flagship devices from the regular ones. It’s probably only a few cents and mainly politics that keeps me from enjoying thinks like this.