“It’s a piece of shit, it’s unusable” like the guy in the video says.

He doesn’t say anything like that. He points out the notice it shows on first use saying it’s unfinished and soliciting bug reports, then ends by acknowledging they’re working for free and it’s a work in progress. Despite the comedic tone, that’s an accurate assessment; PostmarketOS is currently suitable for hobbyists and developers only.

In the middle he tries several times to make a phone call and never succeeds. If anybody is treating this as a serious review to decide whether they should use the same setup around the time the video was published, “unusable” might indeed be a reasonable conclusion, assuming they want to make phone calls on their phone.