Those 2008 disks weren’t great, but airflow advice at that time wasn’t great either.
I can understand how you got where you are, but my concern is that your raidz pools will get more slow as the shared bus fills. You might be able to mitigate this by distributing your pools across different root hubs.
I get the point that external devices will have less heat entrapment, but laying your components in your case to optimize air flow will keep your drives cooler and extend their life. Also, I personally have a lot of risk in my house due to children and pets and can’t imagine leaving my devices out like that.
What size drives and what quantity are you considering?
I am under the impression that Roblox is not compatible with Linux due to anti cheat. I went Linux mint and installed the Linux versions of the top have stores. Steam provides compatibility for many games due to the Steam deck. No issues noted for Minecraft. Haven’t played Fortnite on Linux, but it’s available from the Epic launcher.