> The main inconvenience of fish is not even having to go into another shell for...

> The main inconvenience of fish is not even having to go into another shell for some tasks like virtual env activation

For stuff like "in this directory, I want this virtual env activated", I'd recommend using direnv.

> wondering whether some command you just ran silently did something wrong because of shell incompatibility

I don't recall running into silent incompatibities. Do you have examples in mind?

Although, yeah, you can't just copy-paste most sh/bash snippets into fish.