Yes to speed/distance and basic mapping and ability to download a route and waterproof/reasonably tough. No to heart rate/cadence/other fancy pants stuff.

Is a Garmin edge touring ideal? Or is it a device I will buy and probably never actually use much (just like the turbo)?

I am looking for exactly this with ability to give an OS grid reference so I’m listening!

The touring does what you need it for,and when its working as it should its great,but be aware it does have its niggles( I’ve got a thread going myself about one such niggle )