I generally use Debian based distros such as Kubuntu. Here are documents for attempted installs and use of LUKS and smart cards on various distros. The success rate of features increases with more recent distros and the techniques may be applicable to earlier ones. YMMV
centos has less tools out of the box than deb based distros. Can't find poldi for example.
I prefer Kubuntu but it was harder to get everything working. Ubuntu installs with encryption a little better but still has problems.
PureOS sets many--but not all--features up for me but is limited compared to stock debian or k/ubuntu.
Since PureOS is a product of Purism it makes sense that it is the first to work with the Librem hardware and the security features detailed in these pages. There are not a lot of alternative distros that reach the same level of usability but they are not very far ahead of the rest of the pack. It was a lot of work for me but if you are buying new purism hardware most of the work can be done before shipping. See my page for details.
In summary, (if you can live without some of the usual Linux ecosystem such as 32bit apps and 3rd party apps) PureOS 9 gives the most features of all of these distros but falls short of the hardened, fully featured, user friendly system that Purism is striving for--which is the whole point of the distro. It also suffers a lack of attention from Purism. Blocking Issues and bugs go unresolved for years. Purism staff tries to be helpful but I think the company is too small to keep up with their ambitions.
Using this on the secondary machine. probably wont get pureboot but do have encrypted boot and root with passphrase on boot. Tried to add the librem key but almost trashed the whole system. Might be able to get librem key support by using /boot in the clear like I did with kubuntu.
Ultimately, I'm tired of fighting centos for every little thing I need. It's too much work installing missing dependencies like poldi (and other software I want like powershell 7). Also I hate gnome and kde seems to be broken/dropped lately so that's out too.
got everything working the way I want with 21.10. Some earlier versions crashed on install with encryption. Often have to install using the GTK (ubuntu) themed installer. Subsequent updates and installs have pretty much gone the same. not much improvement when using encrypted drives.
I tried to install Qubes on the librem but couldn't get it to work. Then I discovered that I couldn't get any new OS to work.... I'll get back to it one day...maybe.