I definitely think there's a need for a toy like what you're creating. I currently own a Handy, Syncbot, Autoblow and just got the top selling masturbator on Amazon yesterday. https://a.co/d/i0PGeM5
From my experiences with the varying powered toys I own (I have all the top non-powered ones as well):
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.
As far as my other two toys:
I'm not impressed at all with the Autoblow 2 and the Syncbot I'm most impressed with the build quality, the engineering and the multiple functions it does. The stroke length isn't long enough on it though and if it had a setting to maintain tightness using its squeezing feature then it would work better for me. The spinning function on it sometimes overstimulates me and makes it hard to finish without the proper stroke length. Surprisingly, I can finish easier with the cheaper Handy or even the $50 Amazon toy. I would also say adding a great handsfree ability to your toy would be very helpful too. I have the handsfree option on the Handy and it's too hard to setup and stay in place for me.
Hopefully the qualities I've pointed out from my actual use of some of the top toys out there can help you in your design process.