Fully agree about the S1 as a great source for the Solaris 2020s. SP1000m also sounds great (only heard the n6ii once briefly but it seems to be widely regarded as pretty great).
I recently had a very pleasant surprise finding that the TRN BT-20s pro is actually quite a nice option to turn the Solaris into some pretty great true wireless iems. You certainly don't get their full capabilities like you would with a proper dap or even the S1, but hooked up to the bt20s pro, they definitely blow away any other true wireless iems or headphones I’ve heard. There is no hiss, which was a nice surprise, and you get nice full bass and all things considered pretty great dynamics. I had the older bt20 a few years ago and those hissed pretty noticeably with my OG Solaris and sounded muddy and lifeless. Comfort-wise I have no complaints. The batteries sit behind your ear like a hearing aid battery and pretty much disappear once back there. Battery life was also significantly better than I was expecting. I listened for about 3.5 hours today and still had 80% battery life. All in all they provide a great option for when you are in an environment that you wouldn’t be doing super critical listening or when you are moving around a lot or doing something that makes corded listening inconvenient (like fixing things around the house or working in a wood shop).
As for negatives, the built in microphones are pretty crappy for calls, and I’ve found the usb c charging port in the charging case to be a bit fiddly, making it hard to properly seat the cable to charge it. Also, while it is possible to zip close the charging case when they are connected to the Solaris 2020, you can only barely get it closed and when you do it is tight enough that it makes me nervous about the pressure from the semi-hard cloth case lid on the iems. You probably would not be able to zip closed the case with the OG/SE Solaris attached.
But all in all, as a Bluetooth option and means to turn your Solaris 2020 into a true wireless iems (and one that is pretty affordable at $70), I’m very happy with them. It is also really nice that you can switch out the connector arms so you can use them with mmcx iems or iems with 2 pin connectors. If anyone is looking for something like this, I’d definitely say they are worth checking out.