Well, they're committed to provide as secure device as possible. There's no love for Google in the team.
They recommend Google play over fdroid due to some security concerns, not because they like the service. The reasoning is available on their discussion forum.
And yeah, it won't officially be supported on other devices than the upcoming Motorola and perhaps the next pixel. Too bad.
It's the only news I've heard about new-phone-tech that's gotten me remotely excited in a long time. I'm too poor to be buying new devices though so I'll have to let others do the beta testing for a couple years.
The requirements are not particularly stringent. It is more an embarrassing show from the rest of the Android OEMs that they don't meet basic standards like timely security updates and a decent support period.