I use a Todoist as my idea inbox* because the Android app has a very useful widget where I can add a new note quickly from my home screen. It takes me a few seconds to write down anything I want.
The idea notes have the tag roam because I have a script that runs every few hours and transfers them to today's Daily Notes in Roam.
The idea notes remain in raw form until I review them as spaced repetition cards, where I rework them and expand them.
At this point, they are still not ACID notes but some of them will become one as they get reviewed more and, maybe, be added as a writing idea to my spaced repetition writing system.
It also works as my GTD inbox. During the Process and Organize steps, to-do's remain in Todoist while ideas go to Roam.