p-o-i upstream project have already added puppet 8 jobs (but still non-voting).
The core maintainer (tkajinam) said there is still no full integration test coverage with puppet 8, because of a ruby requirement. But they will reassess the situation.
Currently, we are running puppet 7 on CS9, but it will transition to EOL in Feb 2025 [1].
So we need to build puppet 8 on CS10 and work closely with p-o-i.

From [2]:

• puppet 8.10.0
• Facter: 4.10.0
• Ruby: 3.2.5
• OpenSSL: 3.0.15

fedrq pkgs -b c10 -F plainwithrepo puppet facter ruby openssl
openssl-1:3.2.2-14.el10.x86_64 fedrq-centos-stream-baseos
ruby-3.3.5-8.el10.x86_64 fedrq-centos-stream-appstream

Ruby and OpenSSL versions provided by base CentOS Stream repos are above what's supported currently by Puppet but we'll have to deal with that if possible.
We are already running Facter 4.X.X on CS9, so no major bump for it, thus I expect the build will be easier than in previous bootstrap.

[1] https://www.puppet.com/docs/puppet/7/platform_lifecycle.html#about_agent-platform-releases
[2] https://www.puppet.com/docs/puppet/8/platform_lifecycle.html#about_agent-component-version-numbers