Honestly something as easily accessible as a separate Discord server with each of its own dedicated channels for each department goes a long way for me, something like Google Docs I imagine is also good.
It’s less about the tool and more about how efficiently you can organize yourself, in my opinion. Sure some features can come to be helpful, but the fundamentals are always possible with just writing and basics.
Most of my projects are done solo, so yes.
Not sure how organized a team effort would end up but it depends who you’re working with, if you’re already using discord for communication it’s an easy way of keeping everything within the same tab (communication + documentation/organization)
Pretty handy, but ultimately there’s tons of tools, these just come to mind first, whatever you’re best familiar with will do.