The problem with N-Central Report Manager is that it is only supported using a rather old version of SQL (Something like 2016). If you use the MAPS (Microsoft Action Pack Subscription) you only get licenses for the latest versions (SQL Server 2019)

Inspired by a reddit post

Option 1: Data Export to SQL Server

I would need to check that this would allow to export to SQL Server 2019 but this would be OK if staying in a Windows centric world. I wonder if this would keep exporting and so keep data greater than 90 days.

Under https://<yourncentralserver>:10000/ Setup => Data Export you can configure a connection to an SQL server

Option 2 - Postgres Restore from Backup Dump

A work-a-round perhaps... I haven't as yet tried this but it looks completely feasable

If you untar the nightly FTP backup and go to ncbackup-202112102219-daily\tmp\ncbackup you will find the postgres dump files. (.bin and .schema files)

It would be possible to grab the backup, untar and restore it to a postgres sql db (running on Windows or Linux).

Once you have nosed around the schema a bit and perhaps connected it to something like the open source community edition of Pentaho Report Designer. You could get better access to the data than provided by the default NC reports.

This of course surmises that the data in the dump isn't encrypted or has some other impenatrable obsfucation done to it to make this idea impossible