IDK, Python was fine grabbing list comprehensions from Haskell, yield and coroutines from, say, Modula-2, the walrus operator from, say, C, large swaths from Smalltalk, etc. It does not matter if the languages are related; what matters is whether you can make a feature / approach fit the rest of the language.
Generalized do notation as GP is proposing requires HKT. I don't think it's controversial to say that Go will not be getting HKT.
The := is from Pascal, not C.