I am concerned that quantum computing could potentially brute-force all existing wallets. However, I am unsure whether internet connection speed would impose a limitation on such attacks. If not, how will the Bitcoin community protect itself against this threat? Additionally, how can I contribute, follow existing projects working on this issue, or learn more about this topic?
The best contribution you can do is to read about the topic before creating a new post
It has been already discussed and the conclusion is: There is a risk but there are some solutions for it. The Quantum Computin still not a risk for cryptos because the amount of quibits is low, but in the future the only option will be to integrate the anti-quantum encription created by the nist, there are 3 algorithms made with this propose, you can google them.
https://en.wikipedia.org/wiki/Post-quantum_cryptography