Maybe this is hardware VGA to TV?
ROM chip maybe contain TSR procedure to turn on/off TV output?

or tv to vga (scan doubler)

I saw video connectors and looked at what those feed into, the CXD1172AMs. Their datasheet says"CXD1172AM/AP is a 6-bit CMOS A/D converter for
video use", so my current guess would be a card for digitizing video input. Considering it's ISA it's probably for grabbing single frames, not entire streams. Haven't looked at any of the other chips though, so no idea what else this thing may be capable of.

I tried to look the main 6 in the middle (CS83) and nothing, maybe they are Cypress? that would make them SRAM.
NEC C666GS is also unknown, but used in PC TV thingie http://ohlandl.ipv7.net/video/PS2_TV.html which I think was or included scan doubler
If its either grabber or scan doubler then there should be some Field ram chips around there like in https://threadreaderapp.com/thread/1301990455182155776
cxa1145M is rgb encoder, it generates composite sync video out of rgb input

judging by the chips it does look like VGA to TV, but only two crystals and no PLL circuit would make it a single frame converter?

It looks to me it is a VGA to TV (via cvbs + s-video) card. CXA1145 is for converting RGB to those two formats. CXD1172 are ADCs, CS82LB01 are combination of frame storage and processing, uPC666 are DACs.
There are two 4046 PLL chips and I suppose the PLDs with the logic chips make for all the control timings.