[fstrthnscnd]

The main advantage of Silverblue isn't just toolbox (which isn't originally an Ubuntu tool, btw).

The main advantage of Silverblue is its readonly root fs. Toolbox comes as the provided way for devs to be able to work on top of that feature.

I think Debian has/had some energy devoted to turn the root fs read-only as an option (perhaps in order to move to an ostree based distro, ostree being already available as a package in Sid). Hopefully they'll manage to get it working.

Also, please note that it's not a silver bullet. An immutable FS is a good feature for security (both from malicious adversaries and an oblivious self), but of course it's not enough.