[tvst]

I just have alternate layouts depending on what I'm doing.

English, programming, and some bits of Portuguese = US keyboard + compose key

Portuguese = US-intl (but in mine, all the keys you mentioned are dead keys. No Alt need)

[cassianoleal]

Similar to what I do. On the Mac, I use ABC input source for English and programming (same as US as far as I can tell, but I don't get the US flag on the menubar when it's selected), and Brazilian for PT (essentially US with dead keys, same as US-intl in Linux).

I have a keyboard shortcut to switch.