Web-App that also runs on Mobile?

Hey, fellow developers.
I need a little bit of advice on which technologies I should use for my projects.

I want to create a WebApp that lets you configure some settings (brightness, color,… stuff like this) for my software that I have launched. I thought of a WebApp that runs like Discord, where you can Login to your account on your browser and configure your personal stuff. I also want to launch it as an app in the Playstore (additionally as a App for PC too) so that you can change your settings on your phone.

I did some research and there are so many possibilities on how to implement this so I am a bit overwhelmed.
What technologies would you recommend? I want to do a mobile first approach.