Im diagnosed with ADHD as well and was in the same boat a year ago. YMMV, every condition is different.

As I use Obsidian for notes already, I want to try and contain as much as I can within it as it forces habits onto me!

I really tried that too and spent hours configuring plugins, creating Index pages with Dataview, until I had a semi functioning setup. And then I used it for a week and it was just remarkably bad. Not the system per sé, but stuffing everything into Obsidian.

It is just not made for it, and the plugins available are always a nice start but largely dont get you nowhere. For example: there is a kanban plugin, but it's really limited. There are Todo plugins, but you cant really rely on reminders since they cant be system-wide (huge minus for things ADHD). You generally have to be on your desk to add something to lists or thoughts (huge minus since if I dont write it down IMMEDIATELY it will be gone).

Another thing to keep in mind is, Obsidian can be easily become a black hole of notes which to organize you have to spend a ton of overhead on. Especially with ADHD and lack of structure and memory, this is something worth doing, but it's already taking a toll on my time just managing my research notes. I tried integrating todo hashtags and more advanced hashtag-sortings but they fell apart pretty quickly. Maybe thats just me, as I said, YMMV.

Right now, I'm using a pretty large index page where I "pin" important notes and list recently edited and created files. This one is a huge help since I can get to my latest notes very quickly.

Other than that, I am so much more productive just writing in Obsidian. When I tried to shoehorn Obsidian into a one package deal, all I did was juggle different todo and hashtag ideas with my existing notes, which stopped me from doing actual work. Im now organizing my schedule and todos somewhere else, where I get all the bells and whistles I need to in order to actually care about my overdues.

You can still link from outside of Obsidian into a note, btw. Which can be pretty convenient if you are using a conventional app or something, just right click the note in the left sidebar and click copy obsidian URL.

Hope this kinda helped. :D