this one: GTSM-O Spielplatz-Drehwippe für Zwei ?
I would consider it a special form of playground=seesaw. That’s also what the manufacturer’s name for the play equipment says.
Unfortunately, we don’t have a common/documented tag for things that rotate (for advertising columns we use animated=rotating, but that doesn’t fit here…) rotating or rotable are rarely used, but you could add it.
Anyway, I would avoid “inventing” a new playground value for it, as for me the device is too special and its functionality is too close to existing devices.