All the features that Google ships are necessary for web apps. E.g., open this webpage in different browsers: https://howfuguismybrowser.dev/ — Note that Firefox was once on top of this development, during the days when they also had an interest in developing FirefoxOS. Those days are long gone.

As for what Google has done historically with Chrome, it's trivially easy to point to developments that have improved the web.

You can start with the fact that it's the most secure browser, see for instance: https://madaidans-insecurities.github.io/firefox-chromium.ht...

You can also read their original marketing material, in which they describe the isolation of plugins, extensions, or tabs, i.e., a crashing Flash movie or a crashing website no longer crashed the browser — then count the years it took for their competition to catch up: https://www.google.com/googlebooks/chrome/

On “speed”, not sure what you mean, but Chrome has been demonstrably the fastest browser. It always was, with V8 being the fastest JS engine since launch, but also in benchmarks testing more “real” experiences, like Speedometer 3. The only area where it needs improvement is battery efficiency on macOS machines, where Safari has the lead, but even there it made great strides.

Speaking of PWAs, Chrome was also the first to deliver a good PWA experience on mobile devices and on the desktop. For mobile devices, the first one was Apple's Safari, but then Apple crippled the experience by not implementing much needed functionality, such as notifications. Firefox, BTW, still has unfixed bugs on Android and provides no SSB support for the desktop.