[karl_gluck]

Check out the Winternitz One-Time Signature

Sphere10.com/articles/cryptography/pqc/wots

Signing many things with one identity is possible by precomputing a Merkle tree, but this takes time and the signatures get big.

[er4hn]

SPHINCS+ is a complete signature scheme that carries that idea to it's completion. Shameless plug for where I explain it: https://er4hn.info/blog/2023.12.16-sphincs_plus-step-by-step...