Using OpenSuse Tumbleweed with KDE Plasma on a convertible Chromebook I recently converted, it's been fairly sweet so far.

Something with KDE or GNOME. KDE has better convertible support overall, but currently no working software keyboard (plasma-keyboard is in development tho)

GNOME has no adaptive things, works fine tho and has a software keyboard

I can recommended the latest KDE Plasma, I use it on my 2-in-1. Some quirks here and there, but very good in general, especially if yoh set up gestures to switch between workspaces. I also tried gnome but that was ages ago.

I put KDE Neon on this exact laptop for a friend and everything Just Works(tm). Pen, onscreen keyboard, switching in and out of tablet mode when you flip the lid, everything. Pretty slick really. Same distro on a Lenovo 2-in-1 was a lot more finicky, who knows why

Gnome, extensions make it your way, on touchscreen I like arcmenu with a grid layout, and my dash on the left, always visible and large, easy to tap. I did not like kde with touchscreen, gnome is pretty much setup for it as is and you don't need extensions, just makes It nicer.

Gnome control center is great, standard for touch devices, so you're already used to it. Everythings a bit big and minimal while kde always has more going on on the page and is ideal for mouse use imo.

Congrats on the new gear! I have a 2-in-1 Dell laptop and a Surface Go 2, both running Debian 13. In laptop mode, I really like GNOME, in tablet mode it's... fine. The biggest problem is the GNOME OSK, which honestly is not great. It frequently needs to be manually triggered (instead of automatically opening when clicking in a text-entry zone) and it's missing just about every modifier key unless you're in terminal mode. And GNOME (in its infinite wisdom), decided that the user shouldn't have the choice of when to put the keyboard in terminal mode. There is one extension, https://extensions.gnome.org/extension/5949/gjs-osk/, which helps, but it just duplicates a hardware keyboard virtually instead of providing a fully featured mobile-style keyboard.

On my tablet I use Phosh, which can be installed on top of GNOME and provides a mobile-forward UI and a much better OSK. The Phosh-tablet metapackage in Debian 13 doesn't take up much disk space and, IMHO, will give you a much better touch experience than vanilla GNOME (if you don't mind switching back and forth depending on whether you are in tablet mode or laptop mode). Other than the inconvenience of switching back and forth, the only bug I've noticed is that maximize/minimize/close buttons need to be restored when switching from Phosh back to GNOME Shell.

Zorin OS makes it easier with their Gnome skins and their touch input preset theme.

Its basically Ubuntu LTS underneath the custom UI changes. Similar to Mint's approach, but still using Gnome.

Gnome is pretty much the only game in town for tablet devices. KDE does have a superior OSK in my experience, but overall it's just bad at everything else you'd want for a tablet format.

i did something similar in the past and just used xfce with onscreen keyboard. other options were too dumbed down for desktop usage.

I use Gnome on the two in one. Two in one tends to be useful to occasionally watch a video in tent or some other orientation. The keyboard disable isn't great but your laptop is likely better supported.

Try out Zorin OS.

I can't speak from personal experience but I would recommend this video.
https://youtu.be/nCSs4CbxZHk

I used Ubuntu on an old Surface Pro and it worked really well.