Oh, great to know. That gives me hope that we'll see Ed25519 certificates at some point then.
So on the general web it seems remote at best.
NIST P-curve certs were acceptable per the Base Requirements all the way back in 2012
* https://cabforum.org/uploads/Baseline_Requirements_V1_1.pdf
See "Appendix A - Cryptographic Algorithm and Key Requirements (Normative)", (3) Subscriber Certificates.
Ed25519 certs do work with TLS (OpenSSL support at least), but without browser adoption it's machine to machine with private CA only .