I have several Grundig TKs with damaged (some very badly) cabinet mesh covering, particularly the front section around the speaker.
Quite a while back I did search on the internet and found various materials that might be suitable, the difficulty is removing the old covering and fitting replacement.
Might be worth a post here, somebody must have done repairs/replacement.
https://www.vintage-radio.net/forum/...splay.php?f=21
David