Yes. Sso works just fine across multiple servers-that’s pretty much the point of it.
You can have multiple sites use discourse as the SSO master.
What think you want is to leave all of your WordPress sites alone and add discourse on digital ocean. I’m working on a tool akin to cpanel that’ll let you manage some discourse functions, but it’s not ready yet.
As mentioned above you can get me to install for you (literatecomputing.com) & there’s a digital ocean referral code on my site that’ll give you a $10 credit.