There are several choices:
Cheap Android phones are often sold at subsidized prices, locked to a prepaid carrier. Most of these will work on Wi-Fi and can install apps, without activation. Here’s a $25 example
but most big box stores will have one on sale for $20 or less. There are many other uses for devices like this.
Or, have a friend come over and use his phone to establish the Wi-Fi connection and add the controller to your account. He can then delete the app and you can do further setup and control from any web browser.
Or configure Wi-Fi from your browser; see @zachio 's post here Wont work with iPhone 11 & iOS 13.4.0 then ask a friend (anywhere in the world) to add the controller for you.
I hope that someone will post the API call for adding a controller; initial setup without a smartphone would be very useful.