Debian is very nice these days if you don't mind a tiny bit of enabling non-free repos. Or Pop OS for a more It Just Works approach, if their desktop suits your fancy.

Right now I'm stuck with nVidia's Jetson line of products which is vendor-locked to Ubuntu. The problem is that while you can extend them with a large SSD drive, these products have a really small disk used for /. I could run another OS inside a Docker container, all to avoid this limitation in snap, but of course things will not become prettier.

You've been able to run the root on (nvme) SSD for a while now with Dusty's scripts, and more recently with the official installer.

I have great sympathy though, I am also using Ubuntu on Jetson and resent snap, especially since the new releases are 20.04 which have it more tightly integrated.

You can change the root parameter in extlinux.conf to point to whatever block storage you want it to

Or reconfigure U-Boot to load extlinux.conf (and the kernel image, initrd, etc) entirely from other type of media. IIRC NVMe, USB and external SDs are all supported

Thanks, I'll have to look into it.

Why don't you just mount your big disk on /home, like we used to do in the olden days?

Because I suspect that snap uses both /home/user/snap and /var/.../snap, and needs them to be on the same disk (to allow hardlinking, I suppose).

Have you tried it?

Sounds like something a bindmount might fix.

Back in the olden days before simple and convenient packaging systems like snap had been invented, we had to get pretty creative so that stuff didn't freak out because it was split across filesystems.

I haven't tried it, but I can remember people on forums having mixed results with a bindmount. I guess there is no guarantee that it works until Snap has been running for a while without problems.

I don't see anything there about needing to be on the same filesystem, just that the path is of the form /home/$user/snap. It says that having a home directory that isn't mounted at boot doesn't work, but that's different. Am I missing something?

I'm not sure why you'd need to symlink /home/ to another filesystem instead of just mounting that on /home/ directly, that's what I'm doing with root on ZFS and a separate dataset for /home/ with it's own mountpoint.

Snap also stores stuff in /var/snap, and that probably also has to live on the same filesystem.

Anyway, now I'm working around limitations in Snap instead of Snap working around its own limitations in certain circumstances. The fact that Snap shows weird behavior and illogical error messages in these cases tells me that Snap is not (yet) up to the task of fulfilling this rather fundamental role in my OS.