Add the default GPS to any panel in FS2000 or FS2002.

Open panel.cfg in Notepad & check out the [Window Titles] entry at the top. Here's a typical entry from an FS98 panel.
[Window Titles]
window00=Single Engine Light Jet Instrument Panel
window01=Thrust Levers
window02=Compass

Add a new pop-up window (GPS) to the end of the list. The window number will be next in sequence.
On this particular panel it's window03

[Window Titles]
window00=Single Engine Light Jet Instrument Panel
window01=Thrust Levers
window02=Compass
window03=GPS
Now scroll down & add this entry below the Window02 header& gauges. The new window number must match the one you added under the [Window Titles] header.

[Window03]
size_mm=150,250
windowsize_ratio=2.0
position=8
BACKGROUND_COLOR=16,16,16
VISIBLE=0
ident=GPS

gauge00=gps!gps,0,0,150,250

The entry is actually copied straight out of the FS2002 default beech_king_air_350 panel.cfg with one important difference.
Note the extra windowsize_ratio=2.0 entry. The value controls the size of the pop-up window & associated gauges in relation to the main panel window.
windowsize_ratio=1.0 is normal size, windowsize_ratio=0.5 half size etc. Panels vary a great deal & I have found this a much more convenient method than resizing all the gauges.

Here's how the GPS pop-up looks at windowsize_ratio=2.0 with a main panel window sized 1024 x 768.
Change the windowsize_ratio= value to resize it to suit your own taste. Toggle your new GPS pop-up with Shift + 4.

NOTE. The FS2002 mousable buttons can be added to the main panel to toggle the pop-ups if you wish. These can be sized & positioned manually with a little experimenting. For the buttons to work the exact default [Window Titles] & ident= entries must be used.