The entirety of the question is roughly “it doesn’t work”. Which, as questions go, is tough to build an answer around. It’s also a third-party hardware product, which is usually best discussed with the third-party provider.
Garmin does have at least one (stale-looking) article on USB connection verification, among other troubleshooting suggestions:
https://support.garmin.com/en-US/?faq=zAKcL0VxC65ltPW95ufhG8
There are also some comments about potentially-problematic USB cables, and a (probably outdated stale info) lack of Garmin support for Apple silicon processors (M1, M2, etc):
connect Garmin device to new MacBook Pro - Apple Community
Also about macOS permissions issues:
https://support.garmin.com/en-US/?faq=Lov8UjAnxR1pnz9EJ5kPb9
Garmin has a troubleshooting section in their manual:
https://www8.garmin.com/manuals/webhelp/zumo396/EN-US/GUID-E5BDCF7D-A93B-4007-BDB6-74EE969EBED5.html
”Running Sonoma” covers a whole lot, too. If this is not macOS 14.7.8 (current), update, and remove and re-install the Garmin apps.
The M1 MacBook Pro means USB-C connectors possibly with USB-A docks and dongles for accessing USB-A gear too, and those dongles can sometimes be problematic. This if the Garmin cable is USB-A and not USB-C. Get a USB-C cable, if this GPS supports that, and you’re using a USB-A cable and dongles/docks.
In general, the Garmin website and then Garmin support would be the best spot to look for information on this non-working Garmin configuration, as well. They’re most familiar with the software and hardware.
The existing “This thread has been closed by the system or the community team.” Garmin questions you had mentioned have all likely aged out too, like all older questions do, and the threads were locked to avoid spam, confusion, and stale info, among other issues. All old and inactive threads get locked, not just those older and inactive threads involving a problem that includes a third-party GPS.
