I did this recently, switching from a Pi running Umbrel to an Intel NUC with Openmediavault. Once you realise all the easy to use server bundles such as Casa or Umbrel are just variations of Debian + web interfaces for Docker, it made sense to me to use OMV - it's more barebones, but more flexible.

In terms of hardware the switch was a massive upgrade. I went from an 8GB Pi 4 with 1TB SSD, to an Intel i3 / 32GB RAM / 2TB SSD (dual 2TB SSDs running in RAID 1 for data redundancy).

I wish I could give you a slick upgrade advice, but what I ended up doing was simply manually transferring all the data to the new server once I had it set up. It did take a bit of learning about Docker Compose, rather than using the Umbrel app store. But the range of software available more than makes up for this and it's actually pretty simple.

There are tons of guides available for running Bitcoin and LND in Docker (which is what Umbrel does anyway). The main tip is making sure you close your channels before making the switch. A pain, but best for sat safety.

For LND advice specifically, the Lightning Labs docs are great: https://docs.lightning.engineering/lightning-network-tools/lnd/migrating-lnd