There is no enforcement of any quarantine anywhere in the US. You are required to provide a negative covid test (from no more than three days before take off) before you are allowed to board your flight. You are supposed to self quarantine in a number of states, but no one comes to check on you and there’s no penalty for noncompliance.
The J&J vaccine is one jab but only 60% effective. Even one dose of the two jab vaccines are closer to 80% or more effective two weeks after the first dose. If you have a choice, it makes no sense to get the J&J at this point. But that’s provided you have a choice, which not all states offer. Also, there’s no data on how long one dose of a two dose vaccine is effective for.
Isn’t the Canadian boarder closed to travelers entering from the US right now?