I tried opening the image, but it made my entire laptop unresponsive[1]. So let's hope the graphics manufacturers catch up with the pixel trent before those 8K monitors become mainstream.
[1] On Chrome for MacOS. Granted my macbook is a couple years old, and the Apple graphics drivers are garbage.
Try firefox, it has an integrated decoder-downscaler, i.e. it never has to keep the full-size image in memory before downscaling to the target resolution. But that does not help if you zoom to 1:1.
My laptop is very much bog standard, but gimp had no problem loading it. Generally this may more come down to software implementation, rather than drivers
I don't have too great a desktop (i5 from more than 4 years ago (launch date was apparently 2011) and 16 gigs with more than half already used, no graphics card) and I could open the 291M file just fine in viewnior.
I do have an nvidia card, but since MacOS 10.14 the nvidia driver manager reports that my driver (387.10.10.10.40.105) is not compatible with my OS, and it also reports that there are no newer drivers available when using the update function. So I'm currently back at the default Apple driver.
I have ran the nvidia driver before MacOS 10.14, and it did feel slightly faster than the driver supplied by Apple. I doubt if it will improve opening an 8K*8K image in a browser though...
[1] On Chrome for MacOS. Granted my macbook is a couple years old, and the Apple graphics drivers are garbage.