I recently put Win 98 on an old Compaq that I scrounged because I have software that won’t run on anything modern.
It was a struggle to find a image viewer that would be compatible, but I found FastStone which works great on 98 and everything else I’ve tried it on. I recommend it and it’s free!
Irfanview is also a good picture/image viewer. Older versions used to run under Windows ‘98; there may be a version you can find that works.