one more requirement/restriction - new PDC probably will need to have the same name (hostname)
This just means you want to move roles off and demote, remove from network one at a time. So transfer the fsmo roles from SBS to 2012, decommission and remove from network the SBS following below guidance.
The two prerequisites to introducing the first 2019 or 2022 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
I'd use dcdiag / repadmin tools to verify health
correcting all errors found before starting
any operations. Then stand up the new 2019 or 2022, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can decommission / demote old one.
--please don't forget to
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