The only bikes in the eSS class at Infineon were the Zero bikes.
Once the Empulse / Empulse R are homologated, they could also race in that class. There should be no contest between the two - so it would be like having two spec classes racing at the same time as actual race bikes.
The Empulse RR is only tangentially related to the Empulse R. Different motor, different motor controller (both sevcon gen 4 iirc), no IET, different wheels/brakes/forks/shocks/swingarm, no onboard charger, fairing, bigger battery pack. It does use the same cells (just more of them) as the Empulse R, and I believe the frame is the same.
The eSS Zeros used different tires than stock (still DOT street legal) and had some minor changes to comply with the race restrictions, eg taping over the headlight and forcing the taillight to blink. Other than that they were very close to stock. I don't know if the onboard chargers were removed but I suspect they remained intact.
It wasn't a fair competition - the eSS, TTX75, and TTX bikes race all at once but they're in vastly different realms of preparation. If the race entrants supported it, I'm sure they would be moved to a separate race .. but for now they're just keeping the racing going.
Without the Zero bikes:
* the two TTX75 entrants were no-shows
* the Empulse RR withdrew after two riders crashed in qualifying
* in both races one Lightning bike suffered a mechanical failure and DNFed
Not a good way to start off the race season.