How to get voucher signer with SignatureChecker vs ECDSA

I followed the workshop here

and I arrived to the point where two options are given, ECDSA and SignatureChecker.

From what I understood, SignatureChecker is more flexible than ECDSA because it allows more purchasing options, but I may be wrong.

I am now working on my own lazy mint contract and I plan to use signed vouchers. With ECDSA it's clear that when I receive a signed voucher I can get the signer with ECDSA.recover but if SignatureChecker can be used instead of ECDSA.recover then how do I get the signed of the voucher, as SignatureChecker is asking for the signer as a parameter, data which I don't have because it is in the voucher. I am confused at this point. Or maybe SignatureChecker cannot be used in conjunction with signed vouchers?