I did this back in the days of Smoothwall, ~20 years ago. I used an old, dedicated PC, with 2 PCI NICs.

It was complicated, and took a long time to setup properly. It was loud and used a lot of power, and didn’t give me much beyond the standard $50 routers of the day (and is easily eclipsed by the standard $80 routers of today). But it ran reliably for a number of years without any interaction.

I also didn’t learn anything useful that I could ever apply to something else, so ended up just being a waste of time. 2/10, spend your time on something more useful.