Can I work on this?

Yes, the code for supporting it is most likely going to be in https://github.com/polkadot-evm/frontier

Just to make sure, the implementation of eth_pendingTransactions will go in the frontier repository and the test and others will go in the moonbeam repository? Is that correct?

The implementation goes to frontier yes. For the test, you can also have them in frontier but we usually have more complete test also added to Moonbeam. We can help you with that if neeeded :)

Thanks, @crystalin, I'll start with the changes in frontier

@crystalin I have raised a PR for the implementation of eht_pendingTransactions polkadot-evm/frontier#1540, I am running into a few issues there, if you or a maintainer from frontier repo can help me out with them would be great

Thank you @virajbhartiya .
The team is working on the next Moonbeam release that is coming soon, we will get a look at it early next week.

This has been implemented: #3226

@virajbhartiya thanks for the contribution 👍