I'm in the middle of going down this path right now. It kind of works, except for certain banking institutions require more rigor than just getting accepted into the developer platform.
The steps, as far as I can tell, look something like this:
1) Sign up for Plaid developer account
2) Request developer access (without it you can only play with sandbox data)
3) Request production access
4) Submit application information including a name, website URL, and logo
5) Add a legal company entity name and address to my plaid account
6) Sign an MSA contract (no idea what its about)
7) Fill out a security questionnaire.
I'm at step 3 currently but I'm not sure how much further I'm realistically going to get. I'm not sure I could reasonably fill the rest without stretching the truth quite a bit and it seems to get deep into legal territory that I'm not sure I'm comfortable with.
There's also apparently different API behaviors depending on the bank: https://plaid.com/docs/link/oauth/#institution-specific-beha...
I don't have a lot of hope that this is going to pan out. I'm considering just scraping Chase with a headless puppeteer script instead.
It's possible that this may be simpler for other banks though, I've only tried Chase since that's my primary bank.