My husband had an Amex in the UK and as soon as he got his SSN, before we were even married on K1, he was able to get one in the US with a huge line of credit due to his worthiness over there. so it’s just a time thing using his Amex and all that. He personally hasn’t gotten a credit score yet, but should soon.
if you have the SSN we have apps like kickoff/self to help build credit for $5 a month. I have kickoff myself and it’s built up my credit from very low due to medical debt to ideal in about a year and a half! But if the move you’re wanting to do isn’t immediate, something low cost like that could set you up for when you’re more permanently here. Credit line age and all that.