My kids' interest in it has waxed and waned. Sometimes they loved it, sometimes they had no interest. Fickle toddlers. Getting to a bike skills park with their friends definitely got them excited. Riding in the backyard did not. I was amazed at how hard riding in even short grass was for them with the tiny tires, so riding around in the backyard was their least favorite thing.
Now the older one is 5 and super-into bikes, ripping around on easy mtb trails on his 14" wheeled Pello, and planning bikepacking trips for us.
Keep at it, they'll come around
Howdy Jason! When my kids were smaller I remember them standing over balance bikes around that 18 month range... but really didn't get the point. Something clicked for them around 3 and then it was off-to-the-races. They didn't want to give up those pedal-less contraptions for pedal bikes. It helped that our neighborhood was pretty flat. All the best with your #outdoorkid adventures!