There's already other CAs that (optionally) use ACME to issue. As I understand it from the mod_md readme [1], Buypass basically works (without must staple), Sectigo and ZeroSSL work too, but require an account to be setup.

Are these true alternatives? If not, why not? I don't know where these companies reside.

[1] https://github.com/icing/mod_md?tab=readme-ov-file#known-iss...