Most of the ones (for cnc and sheet metal at least) I’ve used do an estimate while you poke around and select options and then you send it for a final validation and quote.

If you're deliberately creating additional inconvenience to potential customers to handle your own resource/scaling issues... that's a 'you problem', and you need to figure out a better way to run things, or customers will just run to competitors who've already done so.

Right and they already said they have a massive backlog and are trying to increase by 500%.