Apple appears to be sold out of the base Mac mini, and the machine is listed as “Currently Unavailable” from the Apple Online Store. The base Mac mini is the model with an M4 chip, 256GB of storage, and 16GB RAM. M4 Mac mini models with upgraded storage are still in stock, as are Mac mini models that are equipped with the M4 Pro chip. Configurations with 24GB RAM are also still available, but some models that use 32GB RAM or higher are out of stock.
Translation, Everyone buying the base and doing their own drive upgrade. It’s very simple. I did it and a friend as well.