So, it sounds like you might be talking about command+tab since the application is changing (comamnd+tilde does windows in the same application) so if you want to unminimize the application, you hold option while releasing the command key.
since that's a bit hard to parse:
press and hold command
press tab until the applicaiton you want is highlighted in the switcher popup
press and hold option
release command
For snapping to the side of the screen, you need to add the shortcut yourself, but macOS allows you to do this. You need to:
open system preferences
open the keyboard preference pane
open the shortcuts tab
select the App shortcuts category
press +
make sure All Applications is selected in the Application dropdown (should be by default)
enter the following in the Menu title (case sensitive):
Tile Window to Left of Screen
choose your shortcut (highlight the shortcut input field and press the shortcut)
and then hit Add
repeat for the right side of the screen
technically some apps do not support split screen, for those you may want to override the shortcut with the action "Move Window to Left of Screen", overriding the shortcut on an app-by-app basis is done by adding another shortcut specific to that app with the same shortcut but a different action.