[mastax]

For analog electrical simulation there's SPICE. Kicad has a spice tool built in, but I haven't used it. It has some improvements in Kicad 6. I use LTSpice.

For digital or systems simulation there's Renode. You have to recreate the system in Renode,there's no Kicad integration.

[ilaksh]

Maybe with the new s-expressions it will be more feasible for someone to create an importer for Renode. Assuming enough annotations or whatever.