You wont seen OSX soon. OSX from Apple needs license. It is very expensive. You need to pay the license too. I could not imagine how much money we need to develop OSX in Digital Ocean.
Usually OS in Digital Ocean is free (like Linux).
There are many reasons why having access to apple hardware could be desirable.
For example if you are building cross platform applications that targets OSX/iOS platforms you need accesss to actual OSX (xcode only works there).
We have our build server in D.O. but for OSX we are currently looking at services like mac mini vault and macstadium.
This is such a lucrative niche that they don't really need to make a good service, customers will buy their stuff no matter what. D.O. would with their easy to use APIs and offering have a phenomenal synergy by adding OSX enabled hardware in their infrastructure.
Just a thought ;)
I think even at an extra cost for a OSX licence I'm sure there are many people like me who would be ready to pay for it. while you can build Android apk on Linux as of today OSX build have to be done inhouse on a local server or on third party provider that do provide OSX server in the cloud.
In this world of automation, continuous delivery, dockerization, Kubernetes and such, having an OSX build server is a must have.