In terms of "what other apps are doing".
Slightly related is the "Ultra power saving mode" Samsung has on its latest devices.
A very interesting solution when you are trying to desperately hold onto that 2% battery.
Essentially all animations are gone. No colours, no images. Pixels are strictly used to show information in white and black (though not sure if the other way around would save more battery) and you only get access to a handful of apps with mostly Text Based indications.
GPS, Wi-fi and any extra functions are turned off.
Very useful and it actually works!
Opera is a huge proponent of "Progressive web apps". Essentially apps that progressively adjust depending on the situations / device the user is in.
(Read more about them here).
As such, Opera is currently trying to target users in developing countries that encounter connectivity issues or simply don't get access to the latest devices as we do. They offer something called "Turbo mode".
It is a really useful feature and I suggest you test it out and see how it works!
It is one of the reasons Opera now has a large base of users in developing countries within Africa and East Asia.
Hope the above can get you started! It is a very interesting topic and quite a useful feature for users everywhere. I sorta envy you that you get to play with it!