You actually can make simple semiconductors artisanally, once again plugging Sam Zeloof. The biggest trick is getting the silicon in the first place, since you need an electric furnace to smelt it with any efficiency. Then, it's just a matter of distilling it to high purity and growing a crystal.

The pump is the biggest trick for vacuum tubes. If you have a primitive metalworking civilisation to start with, you probably have enough mercury for a Sprengel pump and/or a master craftsman who could make a mechanical pump, but if we're starting really from scratch that could be an issue. Steam to displace air + a chemical getter is another option I've been wondering about.

Also worth mentioning are electrochemical diodes, which you can make with just brine, iron and a piece of aluminum. Aluminum is tricky to make but if you can produce it it's also pretty good for wires, in case you don't have a copper mine handy.