Are there any direct drive (that is, NOT belt-driven) Upright vacuum cleaners for home use sold in the US?

You’re talking about the belt which drives the roller brush?

Every vacuum has to have a motor mounted fan to provide vacuum. Uprights usually also have a belt driven revolving “beater brush” than sweeps the floor/carpet. But uprights also have large bags that let a ample amount of dirt and dust out so that a high rate of vacuum can be maintained. If the bag did not let air out, you would have no vacuum/suck.
If you want a really clean house, you want a Rainbow vacuum. It has a tank of water that collects the dirt and dust, and, since it has this style of filter, it maintains full power at all times for maximum cleaning. BUT! You must clean the filter after every use, ... which isn’t so bad…
I have a Compact Electra that has a common cloth bag, and a secondary foam filter over the motor. It is not a typical canister type vacuum because of the way and angle that the air enters the bag. With this feature, the vacuum maintains almost full power no matter how full of dirt the bag is. Mine used to have a beater bar feature in a removable power head but it isn’t needed. I found my Compact at a yard sale and acquired it for $10. Best money I ever spent! I love the thing! I want to be buried with it!
You might be able to find one at a second hand store, or vacuum repair/sales store.

If you still want the upright, I suggest you remove the belt and the beater bar and run it without those two parts. It will still suck thanks to the motor that provides suction.

I’ve used a Dyson which I believe has no belt. There’s a separate motor inside the brush roller. But personally, I would rather change a few belts than pay $500 for a vacuum.

I have had Bissell for years and have never replaced a belt. I do think it must have a drive belt though. I’m just guessing. I had my first one for 10 years and this one for 6 years, although this one I am starting to have a problem with; it sounds louder than normal the last few months. I have the kind that you can remove the center piece and use it as a hand held.

It’s similar to this one. https://www.amazon.com/Bissell-20431-Powerglide-Upright-Bagless/dp/B06X9F2SR8/ref=asc_df_B06X9F2SR8/?tag=hyprod-20&linkCode=df0&hvadid=198061655183&hvpos=&hvnetw=g&hvrand=13895186572622612889&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9052975&hvtargid=pla-350260176365&psc=1 If you go to the last photo it’s a video.

Mine is a little heavy, but I am much weaker than the average man probably.

I found this beltless vacuum https://www.amazon.com/Kenmore-Lightweight-Handi-Mate-Telescoping-5-Position/dp/B08M2TWTQX/ref=mp_s_a_1_1_sspa?adgrpid=56790033595&dchild=1&gclid=EAIaIQobChMIgYr_o-Xk7QIVxqeGCh1ngwkfEAAYASAAEgL8DvD_BwE&hvadid=274690433439&hvdev=m&hvlocphy=9052975&hvnetw=g&hvqmt=e&hvrand=12620772801011648920&hvtargid=kwd-299596054686&hydadcr=27753_10142742&keywords=beltless+vacuum&qid=1608750151&sr=8-1-spons&tag=hydsma-20&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOU5WSFNHRFZFTERXJmVuY3J5cHRlZElkPUEwNTgyNTI0MVpWN1hFRFRZTVgxQyZlbmNyeXB0ZWRBZElkPUEwNDY4NjgxUzJJR0Y2MVRSM0RJJndpZGdldE5hbWU9c3BfcGhvbmVfc2VhcmNoX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=