Hey there, I'm glad that you've been enjoying the game so much! I hope that if you do get it on mobile you enjoy it just as much:) Personally, I'd say although it is a bit harder on mobile (even though I didn't actually change any projectile speeds or anything, it just feels harder somehow), it definitely suites the game best!
Anyway, as far as the toggle goes... I hadn't actually considered that, but honestly unless a lot of people request it, I probably won't add it, just because settings menu real estate is very precious so I need to only include the most vital settings haha. I could always add a second page or something if it's a popular request though, we'll see!