If we want to go back to a certain history state of the current document , we can scroll the History panel and click each step item, guessing the time, judging by the names of these, the scrollbar position (limited by the capped amount of steps)...
It’s a guesswork in most cases, since some steps still have generic names (like always 'Move' and not 'Move Point', 'Move Handle', 'Move Segment', 'Move Path', 'Move Group'...)

Can I just grab a slider and scrub with it, seeing all the previous states rendered on canvas — and fast? Today Ai sometimes takes too much time to undo, and it won’t work with scrubbing.

And hey — look, Affinity Designer does this.