The shuffle in particular seems to still have a place as a super portable player you use while jogging or biking or whatever, but was hampered in recent years by lack of support for Airpods. I get that the usage model is "just use your phone", but phones are not always a great size for this.
I've considered buying a Shuffle now as I don't really care what order the music is in, but I don't know if the Forerunner I have will connect to it (everything I've read in my cursory search specifically says "phone").
Assuming you mean Toyota 4Runner: As long as your 4Runner has an aux port, you should be able to connect the Shuffle with a male-to-male audio extension cable.
Edit - nevermind - looks like only a single playlist can be synced. That's a pretty major flaw in the system.
BTw in practice I haven't found charging an issue on my 0th gen apple watch and I use it to track both exercise and sleep. It's not "fire and forget" but neither was the iphone for a long time either.
Personally I'm waiting for another month or two to see if the next generation has enough to make me take the plunge.
The Garmin Fenix comes really close to replacing the watch and GPS from above. And it'll run for about a week between charges. If it played music, I'd own one already (even if that meant charging twice a week).
Total 1st world problem.
So what I do now is use an armband as a place to keep my iPhone while running or exercising. The watch DOES let you seek forward/back once you have any music app playing (this works for podcasts as well) so effectively, I use the watch as a convenient "controller" for my iPhone.
Protip if you're oncall/devops: I LOVE the watch when running because I can quickly acknowledge pages from PagerDuty since you can scribble and send text right from the watch itself. Once ack'd, I finish my run and get back to handling the page
Get it now, though. The developer has said the feature was a mistake to implement and is a pain in the ass to maintain, so it might be going away soon.
Does no one make that anymore?