Welcome to the forum!
If you search trident maple I'm sure you will find plenty of inspiration!
But this trunk is off to a good start compared to alot of the starter material we see on here!
Many of us like to build a tree from the nebari (visible surface roots) up.
So my first step for this tree would be a repot at the correct time of year (spring as the buds swell) to lay the roots out flat into a grow box.
This kinda leads to that it would help a lot to give relevant advice if you can include your location in your profile, just approximate such as state if your in the US for example. We have members all over the world, so while it's winter where I am in the UK our members in AUS are enjoying summer!
Formal upright is actually much harder than it seems as a style, informal upright is much more achievable
I would even suggest not getting too bogged down in conforming to a style, and instead make it look like a small tree that appeals to you!
typically if you're happy with the trunk thickness at this stage, (and the nebari is in place) you would then make a chop and build the next section of trunk (thinner than the first) to create taper in the trunk (see images)
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View attachment 578073
If you wanted you could air layer the top to get another tree for your troubles.
Now you will hopefully see how although the trunk leans, the next leader is leaning the other way, so eventually the trunk will go more upright, but with movement.
In fact you may want to lean the first section even more!
Just some food for thought, at the end of the day it's your tree and as long as you're happy with it is all that matters!
You could remove any extra branches so there is only 1 branch at each location to avoid swelling in the trunk (like your pic of the top shows) and go from there with what you've got.
I notice your pics are also inside, I hope that is just for the photography and this tree lives outside?