K/1 students in my district (and many others) use iPads instead of Chromebooks. The website does not work well on the smaller screens.
For Envision, the Interactive Practice Buddy works nicely, but doesn't give the teacher a grade, so I don't use it often. The Quick Check gives a grade, but it doesn't work well visually on the small screen so a lot of my first graders just click any button and turn it in in just a minute or two.
In ReadyGen, the books are hard for kids to read because they don't go full screen, so they're quite small on their tiny screens. The tests and assignments are also tiny for them to read on those small screens. I rarely use the online portal for ReadyGen because it's so unfriendly to the iPad screen.
The SAVVAS Platform is very clunky and frustrating on the iPad. Opening the etext in a new window is slow and only works periodically. The interactives will freeze or not load correctly and when you your reload the students lose their progress and have to start over.
Thank you for the feedback, we are always looking for ways to improve our mobile experience.