join-lemmy.org has a dropdown where you can select language:

https://join-lemmy.org/instances?language=es&sort=most_active

you don't really have to join them, you can just subscribe to their communities

PieFed has a similar browser, but I just see 1 french instance https://feddit.fr/ and none of the other languages you asked about

https://feddit.online/auth/instance_chooser

Portuguese I think the biggest one is https://lemmy.eco.br/, and it's a generalist instance too.

Only instance I can comment on is the one I'm on, discuss.tchncs.de, which is German and English. Has some communities for both languages.

You could also check out the community !ich_iel@feddit.org for German language memes.