My only experience with outdoor model trains is with G gauge and it isn’t good at all.
Before I decided to go with my G gauge I read everything I could find on the subject, there were no negatives. It was fun for about three months. Then the negatives started and never quit.
I expected dirt on the rails and bought a track cleaning car, it worked great for dirt.
The Sun is a killer on plastics. Ants love the rails (their freeway) and when the wheels crush the ants if you don’t clean the squished ants off the rails and wheels their internal juices are acidic and will eat the rails and wheels. Spiders get into everything. Birds do their thing on everything. Pets think everything is something to play with.
My G gauge railroad lasted 18 months and I sold it at a loss, about 50¢ on the dollar.
If you can get in touch with someone involved in these railroads, they can probably help you network with others whose main interest is in garden railways.