If you have a Garmin 230/235 (and possibly others) you’ll know that natively they don’t support any kind of mapping info, however there is a way around this. There is an app (and may be others) called dynamicWatch that can show you route directions, albeit very basically. It only took me 5 minutes to get setup (although it’s a bit long winded, might take others a bit longer perhaps), and now I can import maps to my watch and see where the turns are. It should also update over bluetooth to your watch without you having to do anything extra. All you have to do is download and install the app from the garmin apps site, then login to a website and start uploading routes.
This is the app – https://apps.garmin.com/…/2750f280-82f4-4f21-a32c-57acc7ce4… and this is the website where you sign up, upgrade, plan routes and set which is the active one, and so forth.
You need to know how to install apps on your watch, the way I used was via Garmin Express on my PC but you can also use the Garmin app on your phone. Once you do you’ll get a new menu item on your watch for IQ Apps (if you’ve never installed an app on it). The dynamicWatch app will then give you a url to go to and enter the code it displays, and you’ll need to register an account and give it permission to access your garmin account. Then you’ll be able to create routes and (more importantly) import gpx route files to your account. You’ll only be able to set one route as active at a time (no big deal I guess), but from the looks of it it will update the routes on your watch via the usual BT link from your phone. You can download the routes from the website via the download link under each map (right click and “save as”).
It should work with a few Garmin devices that don’t have native route support, e.g. the the 230 and 235 that I know a few of us have.
It’s not all-singing, all-dancing, and looks like it just shows you your current position and the route outline (i.e. it’s not like sat-nav, it doesn’t tell you when to turn or show you a detailed map). I think you can zoom the map in (my photo shows it zoomed out to max). But it’s better than nothing I guess, and it’s free!
Edit: If you purchase a subscription (there are currently yearly or lifetime options) you can get turn instructions and more advanced features.