There are KVM switches that allow something closer to that at least, but usually only for 2 hosts (pcs). It stands for "keyboard, video, mouse" and they originated in the server space, but recently became common in the home/office as well.
They main purpose is to switch use of the monitors and any attached input devices between PCs. But there are models that allow mixed/shared use as well. If you're looking for one that supports 3 monitors and 3 hosts, with some splitting options, that might be harder to find or cost as rather pretty premium (hundreds).
I bought 48 GB DDR5 for my laptop back in September, just before the prices ignited their rocket engines. I paid 120€ I think. Prices now are like 500(ish). Truly insane.