Upgrading to 2MB Chip RAM is possible, but it requires the 8375 Agnus chip along with some motherboard modifications (easiest if your A500 is a Rev. 6A board). Without this Agnus, 2MB Chip isn’t an option.
On the other hand, 16MB Fast RAM and a 68030 CPU upgrade are not possible with the GVP Impact A500 HD8+, the card supports a maximum of 8MB Fast RAM and has no provisions for a 68030/68882 accelerator.
For modern video output, the Indivision ECS V2 is the recommended choice.
I’m not sure how straightforward it is to replace the original SCSI hard drive with a CF card on this controller, but as an alternative you could look into something like BlueSCSI, which is inexpensive and uses SD cards.
For 2MB Chip, maybe a Megachip board? Anyone still producing these?
As above, for the other stuff. Sidecar supports a maximum of 8MB. I had mine upgraded to 16MB fast by using 8MB 16-bit fast in the sidecar and 8MB 32-bit fast in a CPU-socket based VXL*30 68030 accelerator. It was a hack and a kludge but it worked, until (iirc) my RAM board stopped working due to tinkering with overclocking. It's been a long time since I poked at it. Assume more modern solutions exist now?
+1 for the whatever the latest Indivision ECS is.
I upgraded my sidecar to a CF card using a Mechware SCSI card reader. That was the most direct solution since the Amiga "sees" the card reader just as another HDD. I had to trim a few pieces for optimal fit, but since the power draw was much lower (and cooler) I was also able to ditch the internal fan and the external power supply. It's packed up for nigh on five+ years, now, but am sure pictures exist somewhere on this forum. 😆 BlueSCSI sounds interesting - just gave it a google...
