the only attempt i know of a serious rp scp universe server was pretty based
There was a thread a years ago discussing how such a server would work. As I explained back then, I was working on SCPRP but quickly ran into the issues which keep killing servers - starter factions and headcanons.
Most non-serious servers let players start off as Class Ds, which is awfully boring however, in a serious RP setting you could let players start off as researchers, security officers or service staff and actually keep Class Ds for events, but then you have to avoid becoming Black Mesa RP.
The second issue is headcanons - the wiki encourages viewers to get their own perspective on the foundation and thus there isn't really a single fixed idea of what the SCP universe looks like. This comes to show for example in SCP:CB, which twists many of the descriptions given by the wiki for different things.
Allow me to quote alex directly:
FTRP LOL
Please don’t revive that