Ooh, I think you are going to be in luck. You absolutely have some options and they may not be very expensive. This is "barely commercial" since it basically uses all residential wiring techniques.
So first the obvious: There is TONS of physical space available in that panel for more breakers. The down side though is that it only has a 40a 240v feed which is very limiting. It has four 20a 120v circuits out of it and so that worst case could take up the full 40a of capacity,
It would appear that all the existing wiring is NM-B (Romex) and with the unfinished garage it should be trivial to run new wire.
It appears to me that the panel is a main service panel direct from the utility meter since it only has three wires coming into it (combined neutral/ground). The wire coming in is likely aluminum and actually, the more I look at it, the wire is probably 4awg (please check/verify this!) which at the 75c rating would be good for a 60a electrical service. You may be able to just swap the main breaker over to a 60a breaker and magically get another 20a of 240v service capacity.
And actually, it looks like there is conduit back from this panel to presumably the meter base. It may be possible to easily re-conductor that (likely a short distance?) to upgrade the service to perhaps 100a (swapping from what I presume are aluminum conductors to copper conductors would allow re-using the same conduit. Switching out that wire is likely trivial, though it could require coordination with the power company to shut off (though likely just pulling the meter base which the electrician may be able to do on their own).
We need to see the detailed specs on that panel that is installed there to understand its maximum ratings, etc... I suspect you could just have this popped in:
GE Q-Line 60 Amp 2 in. Double-Pole Circuit Breaker-THQL2160 - The Home Depot
Worst case, that whole panel could be replaced pretty inexpensively. A new 100a main panel can be had for $100 (not including breakers).
Square D Homeline 100 Amp 20-Space 40-Circuit Outdoor Main Breaker Plug-On Neutral Load Center-HOM2040M100PRB - The Home Depot
Note that to upsize the service the main ground wire would need to be be checked to make sure it is of sufficient size, but I think it would be fine for up to a 100a service as is I am guessing.
If you could get a 30a 240v circuit (install a NEMA 14-30 receptacle) using 10-3 romex that would give you a 24a charge rate which should be plenty for most folks needs. (you could possibly also do a 14-50 on a 40a or 50a circuit, but that just gives you a 32a rate with the UMC Gen 2 - the added cost may not be worth it)
So yeah, I might shoot for upgrading that main breaker to 60a, adding a 30a breaker for your receptacle, running 10-3 NM-B cable, and putting in a NEMA 14-30 receptacle. Buy the Tesla adapter for $35 and call it a day!!!