also you can go to files by
am start com.android.documentsui/com.android.documentsui.ViewDownloadsActivity
but the okay button won't work so you need to figure out the X and Y of the screen and run input tap x y
(which I don't know how to do)
I did list packages and the phone does have a package installer
And Scrcpy for this phone isn't great, maybe try with your mouse