Toynerd The Handy does a great job at stroking up and down and syncing, I feel like it has an ideal stroke length but you have to be hard to enter it and it's easy for it to come off during use.
The $50 toy I got yesterday from Amazon does an amazing job at suction, tightness due to that suction, and allowing a totally limp penis to be sucked in and gotten hard. In my testing I actually waited until I was soft, used no porn, cut on the suction and it pulled me in and make me hard. I then cut off the suction and it maintained a perfect tightness due to the vacuum the suction created, I then manually used the device to stroke myself up and down which actually would have gotten me off without the device being on because of the perfect fit created by the suction.
I'm in my 50s so that was an amazing feat to do without porn and without medication.
So if you were able to simply combine the up and down action of the Handy with the suction and auto tightness ability of the $50 Amazon toy, you would have a winner that's better than anything else on market now. Especially combined with your porn synced on the Quest 3 and the fact that the Amazon toy keeps your penis tightly inside with no risk of coming out.
...yea, i've been banging on about suction for years, in my opinion it's the holy grail of scriptable devices, for all the reasons you mention. You might be interested in a machine hack i made up years ago. The thread is a bit old, and needs updating, but i'm still using this set up, and it easily competes with much more expensive equipment like the Serious Kit for fuckability:
Gonna do a big assed thread on ES about scriptable suction at some point soon, will keep you in the loop...