In the US, per FCC rules, it is not officially allowed to listen to other GNSS frequencies as they are not licensed:
> The Federal Communications Commission (FCC) rules require licensing of non-federal receive-only equipment operating with foreign satellite systems, including receive-only earth stations operating with non-U.S. licensed radionavigation-satellite service (RNSS) satellites.
* https://www.gps.gov/spectrum/foreign/
The FCC allowed Galileo use in 2018:
* https://www.fcc.gov/document/fcc-approves-galileo-global-nav...
I think the reasoning is that if it is not "officially sanctioned" then if there's interference with those signals it's not the FCC's problem. By allowing it they'll take noise on those frequencies more seriously in rules and enforcement.