ÖBB trains (even the ones reaching Czechia under Czech Railways brand) are super-good experience.

Yep, can confirm, using the Nightjet was surprisingly comfortable.

The biggest issue is that they tend to be booked up weeks in advance so getting a slot in private compartment is pretty hard.

Which is a good problem to be had right now, from a citizen’s perspective. Proves there’s a market for these trains and we can only expect more of them coming.

This startup is not from the SNCF (national railroad), it's not comparable in terms of service with another national railroad. I'd love to see the project including ÖBB, SBB, & SNCF!