GPX, short for GPS Exchange Format, is the standard waypoint file that Garmin units, Gaia GPS, OnX, and most GPS software actually understand. Google Maps doesn't offer a way to export straight to GPX. The closest official option is Google Takeout, which hands you a CSV of names and addresses with no coordinates attached, so you'd still need to geocode every single place before a GPS device could use it.
MapsLinkQuest skips that whole chain. Paste the shared link to any Google Maps list and it reads the coordinates directly out of the list itself, the same data Maps uses to place the pins on the map. A list of a few pins or a few hundred converts in about the same amount of time.
The resulting GPX file loads straight into Garmin BaseCamp or Garmin Express, imports into Gaia GPS or OnX, and works with basically any GPS unit or backcountry app built in the last two decades.
If someone else sent you the list, the shared list page walks through exporting it.
Want to see the file before you convert your own list? The sample export page has real GPX, KML, GeoJSON and CSV files to download.