Whatever "P5S" is, its page just went up.
presumably separate from The Royal. "P5S" was maybe in that old list of trademarks or whatever but I can't remember. I don't feel like they'd literally call a Switch port "Persona 5 Switch" but who knows. The use of "1 More" maybe signals "one more port" if you feel like reading tea leaves.
April 25th is also like a day after when details about The Royal drop so I guess that'll be a big week.
e: the announcement event for P5S might be happening at Ryōgoku Sumo Hall, if interpretations of code on that website is correct. Ryōgoku also hosts WWE and NJPW shows, among other things pugilistic, no doubt. So, hot take: this could be Persona 5 Arena.