What do you mean by recycled in this case? From my understanding you can pretty much only grind it down to garbage filler and maybe press it into some primitive shape. It’ll never become cling film or whatever again

Polymers can fundamentally be de-polymerized and then you can reuse the monomers, for example see [1]. They call it "chemical recycling". Questionable whether it will ever be price competitive with direct production from crude oil derivatives.

You can also burn them (pyrolysis), collect the carbon and start from scratch. Of course this is insane (economically and thermodynamically), but hey, you are "recycling" the same carbon.

[1] https://cen.acs.org/environment/recycling/Plastic-problem-ch...

If you convert it to solid carbon, there's no need to recycle it any further because it's already harmless to the environment. So perhaps it could be more cost effective than it seems.