If you go iPad, you’ll have to find a way to ‘cast the picture to your monitor if you want sheet music big enough to be readable for older eyes…

I rather think the laptop is your better solution if you want to HDMI to a nice monitor.

But if you have an iPad Pro, that might work as a mobile solution as long as you don’t want to display two adjacent pages at the same time (my preference when reading multi-page scores).

Not sure if UnReal Book runs on both laptop and iPad, OnSong is iPad only, but will network to a laptop for display. Both apps are very mature and well supported. But if no iPad, you might want to research PC programs that do the same thing (I’m only Mac, can’t help much with the Dark Side of the Force!)