Getting significant silicon fabricated is still outside of hobbyist territory. Programs like Tiny Tapeout exist, but the available area and feature size are not "build your own GPU" material.
FPGAs are likely your best bet to start out, although large ones can still get very expensive very fast. You can start out by learning a design language (eg Verilog) and testing your designs in simulation without buying any hardware.
Makes sense that creating anywhere near parity to current tech is out of reach for most people, that's unfortunate but was worth a shot I guess haha
Thanks for the link to tinytapeout! It looks great to actualize once I have a more concrete idea of a chip design
Simulations are the way to go for now I guess, the most interesting part of this exploration is trying to just create strange ISAs I suppose, so it will be nice to iterate faster in the software plane before going to physical
https://efabless.com/tinytapeout
FPGAs are likely your best bet to start out, although large ones can still get very expensive very fast. You can start out by learning a design language (eg Verilog) and testing your designs in simulation without buying any hardware.