2023 is supported in the enterprise edition but not in the community edition yet. We gradually move features from EE to CE as new features added to EE. So you can expect 2023 support in CE in the future :-)
I'm not sure about the timeline because that depends on a lot of things. In the meantime I guess you could start with AUTOSAR C++14. MISRA C++:2023 is essentially built on top of that.
For enterprise edition simply email to hello[AT]naivesystems.com as noted in the README on GitHub