Disclaimer: I have read a lot of these policies but it is your responsibility to read them and understand the insurance you are buying.
Pretty much every certificate I've read on Squaremouth/insuremytrip that is "Covid-19 certified" comes from the same 4-5 underwriters. They all use some form of "medically necessary" for repatriation that means a doctor says you cannot receive adequate care in your current location and orders the return home, and sometimes it's their doctor not your doctor. A few policies let you choose which hospital you go to, but most policies require the plan to coordinate and they choose. They also define a quarantine as a "strict medical quarantine" that is ordered by a doctor for you specifically, such that a positive test alone is not enough. You'd need a doctor's order saying you cannot leave your room in many cases, not just a generic government order.
Covac is unique in that the only "medically necessary" thing is a positive test and one symptom and they'll return you. There are some exclusions you should pay attention to though, such as limitations on cruises, but it's the only one that would reasonably get you home during a quarantine period. Having adequate care on other plans may or may not including having the antibody treatment--it just depends on what the doctor says. Also a lot of policies have exclusions against traveling against the recommendation of government agencies which means coverage might not apply in a level 4 country--check for waivers on the insurer's websites.
So far I've found two unique certificates:
1. Allianz travel, but only with the epidemic endorsement:
Certificate . This plan covers a covid+ quarantine without a strict medical definition as long as you are named specifically, and it covers trip delay for denied boarding due to suspicion of covid or covid+. There is a special bulletin that allows the delay coverage to extend past 5 days (but still only up to the plan limit), and the bulletin also says a covid+ test, even if asymptomatic, is sufficient to cancel. It seems like the positive test is enough to trigger interruption (to pay for new airfare or refund unused accommodations) and delay (to pay for hotel/food during stay extension), but the specific wording in the plan indicates you'd need a doctor's consult for the interruption part of the plan to apply.
2. ITravelInsured Travel SE:
Certificate . This has a unique coverage I didn't find anywhere else: cancellation is covered if a travel level 4 warning is issued within 30 days of departure. It still has the general issue with most plans that covid+ is not enough to trigger anything, you'd also need a doctor (teledoc ok) to order you to not travel, and you'd need a true quarantine to get delay coverage, not just denied boarding due to covid+.
Hope that helps!