We all like a good squeeze now and then ,
...but for hot packing sauces, it's a really tough task. Plastics have a veeeeeerrry small temp window. For most processors, the sauces require a Hot Fill, which does create a vacuum when cooled and plastic bottles (I believe the word I heard was...) "panel". or something about too many bottles were "paneling"~~~ something like that.
Eons ago, I tried working with plastic woozy shaped bottles. They were so deformed they looked like something from an X-Files Lab. Materials have advanced tremendously since the Jurassic Era, but plastics still don't work well for home processors.
Just use the glass and those who want the sauce will pony up for the postage. As always, do not sell or promote a hobby sauce as a legit sauce. Too much potential for problems. There are other threads talking about this very thing. Be safe and keep your friends and family safe while developing the sauce.
First and foremost....Have Fun!!!