I imagine no matter how it's done, it will involve some amount of manual approval. I would be pleasantly surprised to learn that this can be automated.
* The account creator provides a photo id and an EIN
* You verify that the id is valid (visual/ML inspection?)
* Extract the expiration date and make sure it's unexpired (OpenCV/Tesseract)
* Extract the name from the id image (OpenCV/Tesseract)
* Check to see if that id matches the registered agent for that EIN.
This assumes that there is a unified API for EIN/TIN lookup in the US and I don't know if there is.
Honestly, the library/libraries used are kinda moot - those things change all the time (ie, it doesn't matter if it's OpenCV or something else)
Most government-issued IDs are intentionally designed to be very hard to OCR (it's why they have barcodes/etc on them for automated scanning) - and any advances in image processing are more-or-less immediately countered by improvements in ID construction
I know the E-Verify (https://e-verify.gov) service that come businesses use to process I-9 forms (https://www.uscis.gov/sites/default/files/document/forms/i-9...) electronically manages to link SSN, IDs, and other factors to ensure the person filling-out the form matches (as close as can be determined) the data they're filling-in
Credit card, SSN/tax ID, scans of Passport/ID card - some of this is done by online-only financial services (eg Petalcard)
There's also tools like DocuSign, multifactor authentication mechanisms (SMS + TOTP app + email, etc)
If the service/tool is only "supposed" to verify certain types of accounts, you might require the use of specific format email addresses, too (has to end .gov, .edu, nytimes.comm etc) - this can lend itself to organizational verification (gonna be harder to spoof (and therefore easier to verify) harvard.edu than blurblebuck.me)