I would be suspicious of an app if one existed. Although strategies should be ADHD specific (strategies that work for NTs probably won't work for ADHDers, still different things work for different ADHDers. So I think you need to try various things. Also I find that nothing works 100% as strategies and apps don't cure ADHD (sadly). If it works 50% of the time or helps me keep a track of what's going on even if I don't follow it religiously (which isn't going to happen!) then it's a success.
I like things that are very simple. Presented simply without too much clutter. And with just enough reminders or notifications or options to make them useful but not over complicated.
To organise thoughts and recipes and research etc, I use Apple Notes. It's v simple. Layout is automatic (I couldn't get on with Evernote or the Office one - too many options and layout was too wide). You can put notes into folders easily, add links and pictures. And you can "share" to a note from almost any application. And it's always accessible on my phone. I put all our recipes in there, have folders for my family tree research, and folders for notes on our finances, or ideas about the house. It's rare that I can't do what I need in Apple Notes and I like its simplicity and the fact it lays out the note for you.
For to do lists, I use To Do but am also trialling the beta of Superlist (which is being started up by the maker of Wunderlist which was the perfect task list app (imo) unto a Microsoft bought it and ruined it. To Do is OK but it's not Wunderlist. I have high hopes for Superlist I just hope they don't make it too complicated. Anyhow....
To do is the best alternative to wanderlust I've found. It dies most things Wunderlist did. It has a simple interface and it's reasonable easy to set up tasks. The setting due date and reminder functions could be easier but as I say it's only ok and they seem to have stopped developing it further. To do has a great "clear up outstanding tasks" function that's great for ADHDers ... if you have a repeating task and you don't complete it for a while you can just in one click skip to the next task without having to "complete" 100 missed daily tasks! You can set up lists for anything and group your lists and assign tasks to other users. Plus it's free so shouldn't moan too much?!? I can't get Siri to work with it which is supposed to which is annoying as being able to add verbally would be so helpful. But I really couldn't get on with any of the many others I have tried. Interface is super important. Anything too cluttered or unclear and I just can't see anything at all which is no good to me!
Budgeting. Can't recommend YNAB enough. Takes a bit of getting used to but once you do it really simplifies budgeting. You do have to pay for it but personally I think it's worth it. I tried loads of budgeting apps before this one and the key thing for me is that it does the uploading and categorising of transactions really well. You don't end up with shed loads to constantly recategorise and it's also very clear which transactions you need to check and which ones have already been seen by you and confirmed as correct. It also has a "reconciliation" function so you can make sure that your bank accounts and your budget are always in line.
I can't think of any others I use, if I do, I'll pop back. Hope that's helpful.