The details of the design look good. There's a quick-release, so the cover can be rolled up and stored in the gear tunnel.
Not the security of a metal tonneau, but … at least it works … : )
I think most of the "security" of the bed cover is "out of sight, out of mind" … if a scumbag passing by doesn't see you've got stuff in the bed, they're no motivated.
Also, looks like with a different track, this could combine with a rack system (with risers to match the cabin roof height – that's one accessory I can't believe Rivian didn't produce. In my use of a pickup, not that I'm a hard core sailor or a contractor, but I do sail, I own a ladder and I've bought a 2x4 more than once in my life …
Rivian really could just work with Truxedo on an aftermarket solution for people who don't want to pay for the metal tonneau or don't want to lose the space it takes up, reducing the length of the bed. If you can do it in your driveway, I'm pretty sure they could come up with something … : )