Hello, everyone!
I asked around on our Discord server for games recommendations. Here's the list:

GRAN says any of his games are available: 
https://gransvoid.itch.io/galaxy-fighterx
https://gransvoid.itch.io/pantheon-planning
https://gransvoid.itch.io/the-ever-play-fey
https://gransvoid.itch.io/every-wizard-has-a-hat

Lucas Rolim also clears all of his games to be used in the Jam.
You can message him for a key if you want to make content for his paid games!
https://lucasrolim.itch.io

B.A. Reyna says he'll be hacking some games and you can hack these:
https://mundosinfinitos.itch.io/

Igor Coutinho has Helmet up for game:
https://igor-coutinho.itch.io/helmet

Alexander Sheep welcomes content for What a Pickle! and Quinta à Noite:
https://alexandersheep.itch.io/whatapickle
https://alexandersheep.itch.io/quintaanoite

Emanoel Melo has the impressive CBR+PNK:
https://emanoelmelo.itch.io/cbrpnk

Valensa has a Digital Dracula waiting for your blood and data:
https://v-for-valensa.itch.io/cyber-castle-digital-dracula

TheGiftOfGabes could use new stuff for their FantasyPunk: 
https://thegiftofdice.itch.io/fantasypunk

GaboKerr has dueling bards for you:
https://gabokerr.itch.io/duels

Maik cleared up his Moon Elves for new content:
https://maik-malaik.itch.io/moon-elves

Rodrigo also has a bunch of games for you to choose from:
https://rodrigo-o.itch.io/

Tragos Games brings you their games too:
https://tragos-games.itch.io/tyst-borg
https://tragos-games.itch.io/meta

Ivan has an SRD and a rule-setting waiting for extra stuff:
https://ivancoluchi.itch.io/3dr-system
https://ivancoluchi.itch.io/haltera

Kapithan suggests you pile your dice and have fun doing it:
https://kapithan.itch.io/dice-pile-system

Walter Licínio has this player-centered stories SRD:
https://fractalrpg.carrd.co/

Duamn has all this incredible stuff that you can work with:
https://mrdrhobo.itch.io/world-of-blades
https://mrdrhobo.itch.io/and-venture-forth
https://mrdrhobo.itch.io/deep-nightly-fathoms

Wendi has amazingly weird games for you to hack:
https://wendiy.itch.io/marvelous-mutations-merry-musicians
https://wendiy.itch.io/apotheosis-janitors

and last but not least my own Ruin Explorer is up for content or hacks!
Just contact me asking for a key if you don't have it!
https://manchae.itch.io/ruin-explorer

Do you have anything not listed here? Feel free to add to the list!

Push SRD by Cezar Capacle (itch.io)

Great content compilation manchae! Thanks for doing this.

Hey people, if you are still looking for games to hack or create content for rpg latam jam 2022, I've made all my systems on itch free and all of them are available for creation of commercial use! Here are the links and a quick brief of them:

https://maguax.itch.io/minimo-rpg Mínimo is a generic system based of fate where you use fudge dice. It was my first game and still a very accessible one.

https://maguax.itch.io/fingertips Fingertips is an experimental diceless game where you play as magic girls and the dm is a active character that acts as a toxic authority and a mentor. It uses the players hand as a resource for casting spells and winning narrative bets.

https://maguax.itch.io/backpack-e-dream Backpack & Dream is a resource management and exploration ruleset focused on being more of a toolset than providing a guided experience.

https://maguax.itch.io/bxkid BxKid is a hack of minibx by Lucas Rolim. In this game you play as kids pretending to be larping. Its very meta and very self conscious. It has some 4th wall breaking mechanics and it was released during last year jam!

Hi! I’m a latam creator and all you can work with any of my games for this jam, but if I had to recommend one I think Mew Mew Magic ( https://alicesv.itch.io/mew-mew-magic ) is the more receptive to third party content out of my games. It is a Belonging Outside Belonging / No Dice No Masters game so you might already be familiar with writing for these sort of games and since it has playbooks and setting elements it could be easy to add unto it.