With DJI being forced out of the market, there is a growing market for companies that can repair drones and rebuild the batteries. Companies like AG Express are already in this space.
Do NOT throw the old batteries away take them to someone that can make you new ones with the shells Most electronic repair people know how to do it and its actually an up and coming way to make good money.
I wouldn't trust anything in the overhead area. If you end up on a full plane or one with limited overhead space, they may require you to check your bag at the gate.
Even in your country the label must say its safe for distribution FROM A DRONE.
and you CANNOT mix them in any way except how it is stated on the label.
Your country requires a part 102 certificate.
New Zealand also requires you to have on file...