AManNeedsAName
I've tried out their Relay. I don't think they're a scam. I just think they are run by only two people, and are very limited on resources. Their research concepts have been cited by the respected cryptographer Bruce Schneier. One of their founders also co-authored an article with Schneier. It's an interesting read. A cryptographer collaborating with them doesn't make them automatically trustworthy, of course. But I think it adds some credibility to the point that I doubt they are scamming people. They also seemed to have had prior connections with Fastly, so making a deal with Fastly to use their servers as exit servers was likely not difficult.
Invisv made an announcement that they wanted to open source their Relay client, although that never happened. Perhaps they realized the product had no future.
Invisv also seems to not have been successful at marketing Relay. Judging by the Play Store listing, very few people actually downloaded the app. And likely even fewer actually paid for the service, as the app offered a generous free trial with 2 GBs of traffic (and of course reset that counter whenever you reinstalled the app, as you didn't need to create an account). Relay seems to have been poorly marketed, and I doubt the two developers have had prior experience in product marketing.
I'm not particularly interested in their new collaboration with Vivaldi. I wish there were more multi-party relay services for Android, with the usability and speed of iCloud Private Relay. And (hopefully) with decent security.