It doesn't seem technically difficult. Many browsers are native applications and can request hardware information the same way that tools like speccy can. This

It doesn't seem technically difficult. Many browsers are native applications and can request hardware information the same way that tools like speccy can. This isn't exactly what you're asking, but I'd say a lot of sites don't or shouldn't need that information anyway. If you're building a web app that requires battery status or processor architecture or what have you, is a web app really the best format for your program?