Solidity (language for Ethereum Smart Contracts) is relatively easy to learn. There's also tons of free resources in learning them (https://cryptozombies.io/). I would say this would be one of the hottest languages of 2022.
Both ecosystems use Node.js for scripting/tests/frontend so that is going to be advantage to learn.
A good progression might be:
- Modern JS / Node.js
- Solidity / Ethers (https://docs.ethers.io/)
- Rust
- Solana / Anchor (https://project-serum.github.io/anchor/getting-started/introduction.html)