You try to tackle a problem that a lot of people try to tackle.
Example https://itch.io/t/6817612/build-and-indie-game-discovery-and-suggestion-platform
But you put on your approach an additional thing. And that thing might be a restraint or an enhancement feature, with that "mini demo" approach.
A lot of games do not have a well crafted description page.
Most games do not have a trailer video.
Most games do not have a demo version. From the paid only games it is only 5%. (The free games usually do not bother at all, because of obvious reasons.)
So while this is a restraint in many different ways, this would actually work as an enhancement. It would sort out all the devs that can not or will not create a mini demo. But for that, participation would be an issue. Do developers want to participate on the platform with a mini demo version of their game. If you were a big platform and could basically promise a lot of views because of that, sure, there will be lots of willing participants.
Speaking of jams, you might tackle a seed population for your discovery system, by creating a jam with rules of having such a mini game or having a mini demo as an submission entry rule. Of course such a jam and your platform will face the same problem all new platforms face: How to get people to visit ;-)