Question: Required AHI for CPAP with Home Sleep Test

I'm doing research for a project regarding Home Sleep Test devices for the treatment of OSA.

There was lots of information available online on the general classification of the severity of OSA (AHI index <5, 5-15, 15-30 etc), but at what point could / would a doctor actually prescribe CPAP treatment?
Since Home Sleep Test devices are supposedly less precise than PSG, would the required AHI be different for HST (Let's say a type 2 portable device which should be closest to the functionality of an actual PSG examination)? I realize there might also be case-by-case variance depending on other existing conditions, but are there any general regulations in the USA that state specific values such as "if the AHI diagnosed by HST is above xy, CPAP may be prescribed by a doctor. (after a titration study)".

Many thanks for any potential help!

Most insurance companies require an AHI of at least 10 before paying for a machine. Anything over 5 is considered treatable by the medical community. Even with a low AHI, large oxygen desaturations may influence insurance companies to pay for a machine.