To cut it down into a more sizeabnle chunk... The output on the A500 is simple 15HZ RGB, so you can for example use a SCART adapter, but as far as current VGA screens, no, they are Multisync, but they dont go that low Im afraid.
As suggested, you could opt for a scan doubler as this would get the range up to 30 and that should allow a VGA screen to display the pic, but apart from that, its not likely to work no.
Im in a similar boat with my old Atari ST, however, I use a Mono Screen with that so at this time, its not a problem, and my Falcon and TTs use standard VGA Screens. ( Thankfully )