Direct Integration with Bitcoin - #729 by Manu may also be relevant for the readers of this thread: we hope that we can switch to testnet4 soon, which should address some of the issues mentioned here.
Thank you, Manu.
Are you aware of any indexers that currently support testnet4? The UniSat t4 API is not live yet, and BiS is incompatible with HTTPS outcalls.
Hello, UniSat now supports Signet in its API: https://open-api-signet.unisat.io, which means a Signet canister could use this endpoint to work with outcalls.