Something like [Userscript] Self-Study Quiz, and go up from Level 1 (or higher) and see how well you do.
Then choose where to reset to, or not at all.
I don’t regret resetting, as I know I can go back to like Level 60 anyway, with (not-so) speed-running. (Though I don’t, I stopped at 42.)
A large review pile can be tackled bit-by-bit by Sort by SRS Level descending, or less ideally, sort by Level. As long as the pile doesn’t increase (in forecast), it will eventually go down to zero.