The Atom has a Zama carb: C1U P10A 69P
Ryobi engine #1 has Zama carb: C1U P10A 750

I think both of those are covered by the Zama GND-18 kit.

I notice there's none of the metal bits I see in other kits. Some kits seem to have heaps of extra parts other kits don't. (Haven't worked out why yet, LOL.)

The next two I cannot find listed in any of the Walbro kits.

Ryobi engine #2 Walbro carb: 819 WT454
Ryobi engine #3 Walbro carb: WT148A

Also have a Walbro carb on the Tanaka AST-5000 trimmer. It's working fine at the moment. I was just looking for future reference. The parts catalog I downloaded states it is part #: 650-25108-910. But that doesn't help find a kit for it - and there's nothing else (I could see) stamped on the carb itself, apart from the Walbro brand.