> it is really fearmongering when the systemd people literally founded a company to develop attestation for linux?

Considering it changes nothing on what they actually work on on systemd I would give this a yes. Every time I hear "they will do this or that" it just never really happened. So far it feels more like "the boy who cried wolf" than "slippery slope" to me. But maybe I am missing something?

A lot of the devs have always here and there added features for secure/measured boot and image based OSes and things that make them more usable to daily drive (hermetic /usr/, UKIs, sysext, portable services, mkosi, DDIs, ...). A lot of the things make image based systems more modifiable/user accessible without compromising on the general security aspect.

If they really wanted to lock in Linux users to a single blessed image from them they would have had a better chance when Lennart was working at Microsoft (which generally is the only preinstalled CA) instead of starting a "competing" company (they are targeting a different niche from what I understand).