I don't. Huge fan of Larkin Poe, their version of Sleepwalk is stellar, just to name one.
There are so many straps available on the cheap that I would probably at least have a go at cobbling something together.
LOTS of used backpacks out there, maybe craigslist or a yard sale? Our thrift stores are closed for now, not sure about yours.
Padded adjustable straps are available used at minimal cost. I would probably default to my old standby for connecting to the guitar - a stout screw and a washer will hold it in place forever.
I love lap steel too, not great at it but I can get a rudimentary solo onto a recording. I have a tragically butchered Framus 8 string, it used to be a half of my brother's double neck with fancy levers/cams on the bridge so you could flip to different tunings. Sounded like crap though, thin and no sustain. So I found a thick-walled deep socket at a pawn shop for 75 cents, that sounds awesome. It is the second guitar in the attached photo, one of these days I'll take it apart and do some smoothing and rounding on the maple mounting plate. And, here is a piece I played it on for Dr. Walker's Psychadelic Kitchen compilation. I think he had to use it since it was one of just a few entries. 1 track of bass guitar, 4 tracks of lap steel.https://metapop.com/opossum-apocalypse/tracks/that-itch/130532