There are deckhand jobs on many US vessels that do NOT require ANY USCG credentials or a TWIC Card to be a deckhand: vessels under 100 GRT (about 350 GT), fishing vessels, Tugboat’s, etc. These vessels provide new mariners in America with jobs and seatime toward AB ratings.
Another advantage of small vessel jobs is that you will work 12 hour days which will provide you 1-1/2 days seatime credit for each day worked.
Vessels over 100 GRT require a USCG issued MMC. Therexare jobs for entry level mariners as OS.
In order to get an MMC you must get a TWIC card. From what I hear, new immigrants get their TWIC cards faster than American citizens because the TWIC program is unable to check foreign criminal records.
Apply for your TWIC card and MMC as soon as you receive your “Greencard”.
With 180 days of seatime (including on foreign ships) or only 120 (12 hour) days, you can apply for the rating and take the exam for AB OSV (restricted to offshore supply vessels). You will never have to take another exam for AB. You can progress through AB Special (12 months), AB Limited (18 months) and AB unlimited (36 months) without taking anymore exams, just submitting more seatime.
STCW endorsements are issued separately and endorsed separately in your MMC. You do not need them to work on vessels that are: under 200 GRT, fishing vessels, or any vessel operating on the Great Lakes, Inland Waters, Rivers, or harbors.
You will need to take the required USCG approved STCW courses: BT, PSC, etc. and meet STCW seatime requirements to get USCG STCW endorsements for Able Seafarer - Deck in order to serve on ocean and coastwise vessels over 200 GRT.
Job hunting, your Russian credentials and training will usually be an advantage. Being a recent immigrant from a country where people must work hard is often also a job hunting advantage.
I have had very good experiences with Eastern European trained mariners, and for that matter, most recent immigrant mariners.
I do not think you will have any problem finding jobs. There are plenty of “deckhands” looking for jobs, but not many good hardworking deckhands available to hire.