I've shared a bit on this on p.10 of this thread.
First, I called USCIS and got a reference number to open a service request. I was told to wait for an email instructions, but from what I've read on VJ forums, many were denied without USCIS even seeing any proof. (I have never received the email instructions, by the way. Just an update weeks later that the request was submitted and will look into it.)
Then, I immediately contacted my local congressman's office by phone. VJ forum posts were very helpful (look for your local congress page > help with a federal agency for further information). They were very responsive and super helpful and were happy to contact USCIS on my behalf.
Afterwards, I've sent them a cover letter (template also found here on VJ), signed & scanned privacy release form, and a compilation of USCIS receipts and proofs in one PDF (I think about 12-13 pages that included numbered proof backing up my claims of my cover letter. Things like my income before moving here with currency conversions, salary average statistics with for my industry here in the US, my calculation range of lost income since arrival during the K1 process, proof of me running a business with achievements and credentials, pending client contract offers, and other relevant details. Oh, I also included the fact that DMV won't issue a DL without an EAD in my state with screenshots, and why this is relevant for my business - I've even used screenshots of the geographic area where I live).
It took a month but it was very well worth it. So, in total, my EAD approval took 124 days.