I got SM running on ARM on a palm sized board and a USB stick last year experimentally :P
https://portal.smartertools.com/community/a96260/smartermail-running-on-an-orange-pi-zero-3-arm_.aspx

Ever since we've been moving SM to linux I've strayed further from windows. Just VMs now, even at home I have a gaming VM for games. We develop on Macbooks believe it or not. It's been very nice and I reference AI often for various commands still sometimes but I've started getting used to all the commands. So I can recommend referencing AI for learning commands just make sure you give your system details when chatting. I use Ubuntu + Docker mostly except when doing some spot testing for various things.

We do have some guides for moving to Linux and SM itself does a lot of the heavy work automatically if you get all the folders lined up in the correct spots.

Reference: https://portal.smartertools.com/kb/a3691/migrating-smartermail-to-linux.aspx

Edit: I thought I'd include another good strategy lately. You can run a new server migrate domains one at a time into a RUNNING SmarterMail server via the "attach domain" options. This is a bit more manual but allows you to do it at your own pace as domains get moved, this also helps if you have your domains in many different locations. (domains can be moved between windows <-> linux)
Ref: https://portal.smartertools.com/kb/a2726/move-a-domain-from-one-smartermail-server-to-another.aspx