ReadyNAS Ultra 6 - Replace OS with any linux distro or NAS-OS e.g. Openmediavault possible?

Hello community,

model version: ReadyNAS Ultra 6

firmware: RAIDiator 4.2.31

My device is running very well and I don't had any troubles until now, but due to the fact:

1. That my device is very old and won't see any security updates, so I blocked all internet acces for the NAS

2. Firefox tells me that I will soon not be able to log in anymore (TLS < 1.2 will be deactivated)

I'm thinking about what to do with my old NAS to put this device to a more solid and future proof ground. Yes it is possible to upgrade to OS6 but as far as I understand there is always the risk that support for the old devices will be dropped and some guys reporting various problems. In the past I already upgraded but had some issues and so downgraded again.

When I look at my device I would assume that this a completly normal PC, as this test confirms me: https://www.storagereview.com/review/netgear-readynas-ultra-6-review-rndu6000

So why it should not be possible to install another linux distro to prevent another vendor lock-in with OS6?

I remember that I read some time ago that some guys successfully replaced the Netgear OS with another OS but the links which I saves are all dead. I only found in my archive (only as PDF -> website is dead) a "guide" (very short) where somebody explains how he installed CentOS 6 on a ReadyNAS Pro Pioneer edition RNDP600E.

My quesion to you:

Have you experience with replacing the OS from a legacy device?

Any troubles which I'm probably not thinked about?

Thanks in advance!