Speaking as an ex-mod here and current mod on U&L, and having seen the kind of question that is often suggested for migration, I can assure you that opening this path would be a horrible idea. Quite frankly, most questions that are flagged for migration are usually off topic on U&L, or just very bad questions.
In my ~3 years as a mod here, I don't think I migrated more than 5 or so question to U&L. It just doesn't happen very often. The vast majority of cases where an OP doesn't realize this site is Ubuntu only, they also haven't bothered to craft a useful question. Questions that are worth migrating are so rare, it is simpler and more efficient to just flag for mod attention and ask for migration. Or, much, much better: just leave a comment to the OP suggesting they delete their question here and ask it again on the target site.
Migrations are next to useless as implemented. The question retains its original date, so it doesn't appear as new on the target site, it is very confusing for users and especially those with no account on the target. The whole thing is just more trouble than it's worth. So no, moving would absolutely not be a better experience for the user, more often than not, moving results in an orphaned question.
There is essentially no benefit whatsoever to opening a migration path and there are significant downsides.