So the first one is doing PSTB on a dedicated machine using Ubuntu or some other distro? This is where you’d keep most of your bitcoin?

The second is the same as above but you don’t have to use PSTB.

But can’t hardware wallets be used in place of a dedicated machine? And don’t machines themselves even offline have certain attack vectors and vulnerabilities? (Though highly unlikely)

For the 3rd what’s your assessment of startOS? Thanks.