Please get acquainted with the protocols which are available to solve the SBHACK21 challenges:
Algorand:
https://developer.algorand.org/
NEAR:
https://hackmd.io/@nearly-learning/near-201
Streamr:
https://streamr.network/docs/getting-started
Onboarding video: https://youtu.be/pRx-kqghgHk
Extra tutorial video: https://youtu.be/WHmCSKq2CdI
Velas:
Casper: