They went with OpenDesk, which uses Nextcloud as Cloud System.

Where have you read that they are going to switch to OpenCloud?

Yes. There are enough signed and exploitable Windows Boot loader which you can use to boot anything you want.

And for containers auto updates once every day.

Got apticron set up on my servers or similar solutions to get notified when updates are available. Then usually, from time of notification +1 or 2 days.

Luckily thanks to their licensing model they basically cannot. Immich has according to github as of now 1606 contributors. Changing the license so that there could even be a proprietary fork would require basically the ok by every contributor (that made a relevant code contribution)

Just because an app is old, does not mean that it is not usable or bad. Let’s look at games for example.