My advice to you will be you should likely look to getting a Developer Account/using a free one from something like AppDB. I am not sure how things will be with sideloading, but services like AppDB have plenty of options sideloading pirated apps. I'm sure that will be updated at some point for wearOS.
The big "but" in all this, is unless it requires you to tie it to an iPhone/Mac, there may not be a way to extract ipa files to sideload.
If you mean WATCHos, then yeah. AppDB sideload to an iphone. Example is like Calcbot 2, you can sideload it to your phone and use the watchos app cause its on your phone.
You need to go to private communities like GGn