Main thing I've encountered recently is they need to be in carry on not checked luggage. Some airlines also won't let you fly with a bunch of batteries not attached / same bag as equipment they go on.
It may be a good idea to put them in lipo bags but think you'll find it's not in most of the regs.
From a practical standpoint almost all of the recent airline issues are batteries in the cargo hold, jostled around and one of them shorts. It difficult to short the solos smart batteries but you can always tape across the terminal sockets to prevent something else in a bag from somehow shorting them. Makes the bag inspectors feel better too if they pull out your carry on at security.
I've flown 4 flights with solo and 5 batteries in the backpack carryon. Jetstar, Hawaiian, Qantas. Lax, hnl, Syd, cbr.
Just watch out for if you end up on a prop job somewhere like a dash-8, where it won't fit in the overhead bins, it will end up put in the hold on the Tarmac with priority luggage and asked at the gate, so no lipos? Ahhhh.