Panasonic FX90 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, GoPro Hero9 Black has a
23.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features GP1 processor.
GoPro Hero9 Black's sensor provides 11MP more than Panasonic FX90's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the FX90 and Hero9 Black sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic FX90 and GoPro Hero9 Black Cameras
Panasonic FX90 and GoPro Hero9 Black have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Panasonic FX90
or the
GoPro Hero9 Black ,
including hyperfocal distance.