There's an old, but fairly comprehensive, consumer report article from 2011 that concludes: "When Recursion’s security experts tested 10 types of shields and wallets currently being sold to protect contactless cards, they found that none blocked the signal completely, and there was dramatic variability even among samples of the same brand."
I don't know if the situation has improved much since then.
> they found that none blocked the signal completely
You can not block ths signal completeley. It is just the nature of radio wave that some small amplitude will get past the barrier, but you can lower the signal-amplitude so much, that the signal is worthless and a passive rfid chip will never respond.
Alas, with a very strong sender, you might get through, but that is more a theoretical possibility or for the truly paranoid.
I don't know if the situation has improved much since then.