I got a TRTL "pillow" on Amazon before Xmas and planned on trying it out when I flew home for the holidays.
Ended up not taking it because I filled up my tote bag with extras because of the cold and couldn't fit it in. Wanted room to put my jacket in the tote once in the airport. I also usually put whatever I'm using as a purse in the tote.
I have tried it out on the couch. Seems okay if you get the positioning right and it's tight enough. I have a short neck. Seems like it might get a little warm in the summer or on a warm flight. It has a removable, washable fleece cover and fastens around your neck with velcro.
I've used an inflatable before. It loses pressure once in the air. I don't like having to inflate it in flight. And with COVID still around, I wasn't going to remove my mask in flight anyway.
Flights weren't that long and I had a book to read.