R360 - post-upgrade with BOSS-N1 and re-install of WS2025 problem

Hi,

PowerEdge was delivered with 2x3.5" 4TB drives pre-installed with WS2025 by Dell in a RAID1 config with H355 controller. We spit it up with a 100 GB partition for OS and the rest for data+VMs. We have since decided to upgrade the R360 with BOSS-N1 controller (customer+enablement kits) e.g. 403-BCSC and 490-BKKM.

I'm using the BOSS-N1 as RAID1, and have configured the volume in System Setup during boot-up. I then re-installed WS2025 from the install media provided by Dell.

When install was complete, the reboot was not succesful - it started from the old installation on the H355 RAID config, and it seems to be impossible to boot the just installed WS2025, eventhough the BOSS controller shows up in Boot Manager.

I did not go the route of "Deploy OS" in Lifecycle controller since I could only select WS2022 as the most recent operating system despite having installed the latest OS Driver pack, no WS2025 option.

The purpose of the 2x4TB RAID1 HDDs will be for file storage and the plan is just to delete the OS partition after the BOSS-N1 RAID1 setup is running and then just expand the data partion for VMs.
Would someone have a better approach to this? Disable the HDD RAID array or delete it prior to the BOSS-N1 install? Really hesitating to do something wrong here, even though I do have backups of the virtual machines...

Thanks!