The Wahoo Mini is basically the successor to the RFLKT.

Can't speak to Garmin, but the Bolt downloads the routes that are created in RideWithGPS, Kamoots, etc... so the navigation is conducted soley by the head unit.

I think there is a mistaken assumption that since the Bolt connects to your phone via BT that it uses your phones resources while riding (ie at the same time). That is not the case. The BT connection is there only to setup your Bolt, to auto upload your rides AFTER it is complete, to download the routes you created in RWGPS/Kamoots, and software updates.

It does not require your phone to record your ride or to navigate.

Not required for operation, but the BT connection will be active between device and phone if using Live Track or Notifications. My reading is that it’s not a noticeable drain on either device or phone battery life.

It is what they replaced the RFLKT with but it's a stand alone computer. Other than paring for setup and notifications. The Mini will work without being connected to a phone. The RFLKT had to be connected to a phone with a compatible cycling app in order for it to work.

If you’re using your phones GPS it gets wicked hot and sucks battery.
I highly recommend the Wahoo bolt. Was/is worth every worth penny.

That sounds like progress to me. Why would you unnecessarily want to use up phone resources and depend on GPS signal quality coming from your pocket?

While that is progress for Wahoo, the point I wanted to make is that the Mini is not what the OP was asking for, while the RFLKT is. Fortunately for him, he went with a Bolt, as did I. However, at the time it was released, the RFLKT was a perfect answer for those that did not want to spend $200.00 plus dollars on a GPS computer when they already had the same functionality in their phones. Leaving the phone's screen turned on while riding will drain a battery in no time and the RFLKT was the solution to that problem. As I mentioned in a previous post, I used a RFLKT connected to an iPhone (5c and 6 SE) for about 5 years before it died on me. I have done several century rides and have never had to charge my phone in order to finish one of those rides. Along with the RFLKT, I also had a HR, speed and cadence sensors connected to the phone and still had enough battery life left on the phone to make several calls, if needed. And with the Mini, if you want to track your ride, you still need to use your phones GPS in order to do so. So basically, using GPS on your rides with the Mini, you're really not saving a hell of a lot of resources.

I still use my phone and Cyclemeter to send my location to my wife on charity rides and other rides longer than 50 miles. Live Tracking, using the Bolt and continuous streaming over a cellular connection, completely drains my phone battery in less than 30 miles. That's never happened using my phone since I can set Cyclemeter to send an email (and update to their server) at specific time or distance intervals, thus limiting the cellular connection time and usage.

I think the RFLKT, and/or devices like it, still have a place in cycling for those who want the features of a GPS computer but don't have or want to spend the extra money for them. It's unfortunate that Wahoo decided to leave those potential customers behind and go strictly with standalone computers. The RFLKT had some issues, but nothing that Wahoo couldn't have worked out.