There are quite a few, mostly meant for industry applications where there is a controller card for a specialized device, e.g.: https://www.nixsys.com/motherboard-with-isa-slot/

Though you'll find that a lot of them are single-board computers meant to interface with a bus backplane, either PC/104 (as the sibling comment notes) or... more advanced, like this thing: https://www.advantech.com/products/1-2jkn6l/pca-6028/mod_e93...

which will accept aCore i7s and 16GB of RAM, and has native ISA.