Just wondering if anyone has an old one lying around that I can buy? Feel free to PM me if you do.  Looks like it needs to be on this list:

https://en.avm.de/nc/faqs/which-fritz-products-support-mesh/

Would probably run a cable from my existing fritzbox so am OK with the ones that say "only with network cable"

It's not clear to me if the ones that say "only in router mode" would mean double NAT? But one of them would probably be OK too. 

(If noone has anything all good, will probably get the repeater 2degrees is offering. Just thought I'd try here first)