Funny that you posted today-I’ve had a seedling I ‘found’ somewhere in our gravel path earlier this year. On a whim I pulled it up and put it in the grow bed, having no idea what it was, other than it was growing quickly.
I believe now that it’s a red maple based on your pics - I’m not aware of any red maples near me (only sugar). But, maybe a bird brought the seed??
It was extending a lot, but the deer got to it. Interestingly, it threw a number of shoots from the base.
Now, I’m thinking that this might become something - your progress has been impressive in pots, maybe a few years of ground growing…
Thanks for posting-it’s motivated me to continue working with this.