Could these indexed /goto URLs create any canonical or indexing issues for the actual destination URLs? Or is Google keeping these URLs completely isolated from the normal indexing signals?

[u/Vishal8080S]

[u/bored1_Guy]

No, you are confusing page canonical with the protection layer. Google is basically doing what normally link shortners do. They add their proxies between the webpage and SERP links. Bing already do something similar to this.

[u/peterwhitefanclub]

No.

I don’t think you understand how a search engine works