Read through the docs: https://learn.microsoft.com/en-us/sql/reporting-services/install-windows/migrate-a-reporting-services-installation-native-mode?view=sql-server-ver16
Basic things to know / have backups of...
- encryption key
- Any custom reports
- You might need to update the datasource on restored reports (if that's what you choose to do).
I think that's all covered in the docs, but basically, read the docs, follow the docs, and you'll be fine.