It is actually currently available, at least in the US. For 17$. But maybe not Norway, sorry. I realize that trying a lot of things can be tiresome; that's why debugging things doesn't always get done. I was going to go ahead and try the nvme route, but this m2 sata thing worked, so didn't bother.
As for ext4 - I bought a nifty little extension application for my mac from Paragon software that adds ext4 support. They also make a similar app for windows I believe. Beats the hell out of starting up a VM.
I will try ext4 on my SSD and post the result here if it actually makes a difference. Installed Ubuntu on an old laptop to be used for transferring music.