Last week I tried the Spencer Meadows National Recreation Trail, which is absent from all Garmin maps. No problem, I used AllTrails - Spencer Meadows. But I lost the trail on AllTrails at a stream crossing due to all the ash etc. When I finally found the trail again, I added a Saved Location on my F7SS and InReach Mini 2 via the iOS Explore app where I lost the trail before, as a navaid to easily get back later.
When I tried to navigate to the Saved Location during the Hike activity, I found no way to just route directly to it. Every attempt gave me a crazy road detour way out of scope - "walk x miles left, take the road 0.5 miles, then walk x miles right to reach your destination". This makes using Saved Locations in the backcountry for hikers and backpackers virtually useless, and even dangerous - set a location and find later you simply can't navigate to it effectively.
I see from 4-5 years ago that older Garmin HW/SW supported direct navigation in activity settings (here, here, here) but more recently (like this) it seems to only navigate if routable, which as the latter post shows, causes some problems occasionally even when Garmin-known routes may exist.
I've talked with Garmin briefly about this issue and will "share an idea" that maybe a high-end watch used by hikers and backpackers for navigation, should actually support the standard options for navigation that Garmin and other GPS units have had for a few decades. But if anyone knows a good way of doing this now with Saved Locations, please do chime in! One option I've heard about is to always use Courses rather than Saved Locations. Even a single-point Course can act as a directly routable Saved Location, I guess. Creating these on the fly in the backcountry isn't necessarily a problem. I haven't actually tried this yet though - and Courses have different limitations than Saved Locations so it seems the solution is "when the only tool you have is a hammer, every problem looks like a nail".
