What's wrong with "webapp to configure a keyboard"? It's the same as "app to configure a keyboard", just with another option to run it straight from a website, without installation.

It made possible when chromium-based browsers (Chrome, Edge, Opera) implemented WebHID API.

Now, if I couldn't download it and run myself, that would be a different story (vendor lock-in). But I can, so I think WebHID is godsend.

PS: By the way, the most popular RC (quadcopters/airplanes/helicopters) flight controller configurer is https://app.betaflight.com/ . It's a pretty complex tool with a tons of bells and whistles.