Oracle Linux (up until 9.3 I think?) is a direct clone of RHEL. After 9.3 (or maybe it's 9.2) it's a best attempt clone of RHEL (similar to Alma Linux or Rocky Linux). If you want to learn RHEL then it's a fairly decent equivalent with a couple of their own quirks thrown in (ULN, ksplice and the UEK).
Also, I don't bother with certs or care if people have them. I have yet to find someone who knows a product better having got the cert than someone who's used the product without a cert.
That's really interestng. I assume it's the left photo from above and the right photo from below.
https://en.wikipedia.org/wiki/Gynandromorphism
Genuinely an interesting mutation, it's weird that it's listed as happening in Rodents but not other mammals? Is that just a numbers thing I wonder?