Why "restart" and not "factory reset" the remote
Roku publishes an article for restarting a remote and none at all for factory-resetting one, and that gap is meaningful rather than an oversight. A remote holds almost no state: batteries, and on wireless models a pairing to one player. There is nothing else in there to wipe, so the procedures are drain-the-power and forget-the-pairing, which is what the restart and pairing gestures respectively do.
That is why "factory reset my Roku remote" turns up so many contradictory answers. There is no such operation, so every article invents its own. The two things that genuinely exist are the twenty-second hold on rechargeable models and the batteries-out-press-two-buttons sequence on battery models.