I think the Green's have 2 big problems.
1) Nuclear policy.
2) Hypno-breast enlargement.
Corbyn telling everyone he'd never push the nuclear button disqualified him as PM for a lot of people. No one wants somoene with an itchy trigger finger, but people still believe in MAD, and with tensions with Russia the highest they've been in 35 years the idea of being a defenseless target is going to turn a lot of people away.
The hypnotherapy story is just poltical krytonite, it has that Thorpe affair combination of being sexual, funny and deeply unserious, and the worst thing you can be as a political leader is a laughing stock.
If Polanski can genuinely shake off the hypno story and they really hammer home that their nuclear policy is simply no first strikes (and maybe revisit nuclear energy policy) then they could get somewhere, but until they go fully mainstream and Labour/Tory/Reform media machines really start gunning for him it's hard to see them even getting as big the Clegg Lib Dems.
They do also have a lot of weirdos in the party, I think they'll suffer from the same kind of drip feed of mental candidates/local gov politicians being unmasked that reform have.