something like this for the switching
https://www.amazon.com/RetroArcade-us-Arcade-Control-GBS-8118-Switcher/dp/B00F1YQMQQ
one of these for video
https://www.amazon.com/DEVMO-GBS8200-Converter-Monitor-GBS-8200/dp/B07TWZBQ75
id just get a monitor that has vga and save yourself a second conversion to hdmi
and definitely Portrait mode, should be able to fill the screen with the gbs-8200
i usually use these power supplies