I have some Specialized toe covers right now, have used others is the past. The stop the wind and have a bit of insulation. For socks I am using 7Mesh Merino wool, would call it medium weight.
GripGrap spatz are the cheap neoprene version of these. Next to skin and then over the top of overshoes or winter boots and thereās no leaking of water down your leg into your sock
I gave up on overshoes/booties and use waterproof socks. I have merino lined lightweight CrossPoint brand. Work very well, but you need enough room in your shoes for them
I use a pair of POCās thermal booties for my wet rides above 8°C the OP mentioned above. If it is too cold though they donāt keep me warm enough and I end up using winter shoes. POC has a heavy duty version that is supposed to be warmer, but I havenāt tried them. Black linked here, but also come in the POC orange (20% off available through the member purchase program): https://poc.com/en-us/product/thermal-bootie-uranium-black
Iām not 100% pleased with my winter shoes, but they end up keeping my feet warmer than the booties. I havenāt used them in really wet weather. When itās that cold and rainy, I opt for the indoor trainer.
Iāve tried waterproof socks once, but my feet froze. I think they were too tight/compressive and restricted circulation. I need to get a different pair, not so compressive, and try again I think.
Iāll also add that I ride with fenders in the winter. Many benefits and cutting down on the spray from tires to your feet is one of them.
Instead a neoprene cuff worn next to skin and over the top of the boot or waterproof sock is the answer. Grip Grab sell a pair very reasonably priced and they work really well!
Nothing is REALLY waterproof. It will get in eventually. having a good set of mudguards is usually the kicker that will help keep you drier for longer.