A while back I linked to a cheapo trick of using a guitar wireless transmitter/receiver as a wireless IEM. That one was mono and a bit clunky, but works pretty well:
https://www.youtube.com/watch?v=uXTZNY5Ta-o
I saw a stereo transmitter, so I thought I'd try it for this application, since I'd like my nice lush choruses & reverbs to come across in stereo. I tried this one, but there are a few different versions around $40:
https://www.amazon.com/LEKATO-Wireless-Transmitter-Receiver-Rechargeable/dp/B08FDQ2VHW
Results: It's ok. Kinda meh. Here's why:
1. This model doesn't have a headphone out jack like the mono one in the first link; it has stereo 3.5mm plugs (with 1/4" adapters). I used a 3.5mm "gender bender" to plug in my headphones, and the plug folded up out of the way nicely. The problem is, the output is much lower than the mono model. When you crank up the output of the Helix's headphone out to get more volume, you start to clip the transmitter. So it's ok if you listen softly or have very efficient headphones, but not if you want to crank it up with less efficient ones. This makes sense; it was intended to drive an instrument input, not a set of phones.
2. Both the mono one and this one have about 14ms latency (I split the signal and measured it on my audio editor). That's ok to my ear UNTIL you add in the latency from any wireless transmitter you're actually using for your guitar. My 5.8GHz transmitter has 7ms latency (I measured that, too), so together they're over 20ms. This is ok for slow picking or strumming, but once I start chugging it gets a bit bothersome. I'm not sure why it didn't bug me when I tested the mono model. Maybe I was using a cable to feed the Helix. Maybe I had less coffee that day. I dunno.
So, no free (or cheap) lunch. Given what's on the market (and my PC desk!) now, it seems to me that a 5.8GHz stereo IEM with 7-ish ms latency should be possible. I'd buy one if it were under a hundred bucks.