I have done my work as a webmaster aggressively in the past. From time to time, I use my old phone to use the internet, and the newest sites never work on my phone (which I can't be surprised of), but my site runs on every phone. I think about everyone. I'm sorry owners of commodore, I haven't supported your system.
But anyways I want to somehow create something of some sorts on my website that will allow search engines and other website data collectors to understand that my website is fast and compatible with nearly everything. Many websites today are geared to work with only newer browsers.
I understand there are tools like Google page-speed insights and webpagetest.org but I used all of those to test my site and to help me make it fast.
I'm willing to add a line of extra HTML in my code or even a special HTTP header if that helps search engines recognize my site more.
Does anyone have any suggestions on what I can do to tell all search engine bots out there that my site is backward compatible with older browsers?