Is it possible to use a snapshot of the relay chain to synchronize a Substrate-based parachain and run a parachain node, as the process of synchronizing the relay chain can take a significant amount of time?
Yes you can use snapshots, but I would recommend that you are using warp sync:
your-parachain -- --sync warp-sync
This will make the relay chain node use warp sync. This is much faster and should only take some minutes. We are also working on warp sync support for parachains right now. This will then make it possible to warp sync the parachain and the relay chain!
Yes. It is possible. You can find snapshots here https://polkashots.io/