The 'real-time supervision' requirement for COVID travel tests

I've finally bought a plane ticket to visit my family in the U.S., and I'm SO confused trying to work out which COVID test will be accepted for travel. I'm looking at Randox, because they have a drop off lab near me. (I know others on here have recommended Qured, but I CANNOT get registered on their site for the life of me, there's a bug with the site or my browser or something.)

The CDC guidelines say that if you do an at-home test, you need a 'telehealth service that provides real-time supervision'. But Randox does not do this, they simply provide instructional videos. Is this going to pose a problem somehow, will my test not be accepted as valid if I use them? Can anyone recommend a provider they know from experience will be accepted?

Also - does anyone know how long you can store an at-home PCR test? Wondering how early I can order my test. Thanks!!

That must be new guidance as I hadn't heard about it must be a telehealth service, unless I missed it.

I, personally, would try again on Qured, with a different email address or something. They are very convenient and you know they meet US requirements and UK, also.

The tests can be stored for weeks as everything is sterilised and hermetically sealed. You just cannot take the test and leave it without sending.