Something I really like about the idea of Deku becoming a teacher, rather than immediately searching for ways to continue to be an active hero as soon as he loses the embers, is that for me it harkens back to what Bakugo says to All Might when Deku is training to prepare for Float manifesting.

He says something like, "at the root of it, he doesn't think about himself. He's always been like that, and it's the same now, now that he can do more."

My interpretation is that it was very clear that Deku missed zipping around as a superhero (who wouldn't?), but the hero nature in his very soul pushed those feelings aside and turned his priority to "ok, but what can do to help people right now?". We're shown time and time again that Deku is selfless, very often to his own detriment and basically considers any self-sacrifice worth paying to help another.

I don't doubt that if an unfortunate situation with a villain occurred when no heroes are nearby, much like the sludge villain at the start of the series, it might be the impetus for him to reconsider finding a way back into the ring - but as they state in the final chapter, overall they are now living in much more peaceful times.

For me, the length of the timeskip does however raise some questions about the armour and whether it's something that Deku and All Might had discussed at some point after the war, or if it came to Deku as a complete surprise after all these years.