SPICE is a general-purpose, open-source analog electronic circuit simulator. It stands for Simulation Program with Integrated Circuit Emphasis.
ngspice is a successor, and is easily installable on Linux. It’s the simulator I’ve used to explore the Skywater 130 PDK.
Here’s an example spice simulation file that I used to simulate the inverter I drew.
And here’s a nice demo of me showing how a flip-flop works by simulating a Sky130 D type flip flop with SPICE.
It was a great fun way to introduce people to Verilog and basic digital design in general. You don't have to have done tons of FPGA stuff or be an expert at Verilog at all. If you’re interested in hardware in general I'd say it's accessible.