This makes zero sense to me.
Even if you have managed to create an instant and frictionless mechanism of selling ETFs the moment you need to spend on something and are providing people with the liquidity while their brokerage completes the sale and transfer I can't see the value here. Most people don't want their daily spending money in something that has price instability. The reason people suggest that your emergency fund is in a HYSA is not because you can access it a few hours faster. It is because you want some insurance against needing the money after a 25% dip. Worse, your homepage advertises individual stocks and bitcoin!
And if people do want this behavior then you've enabled people to earn another like 0.03% by keeping money invested for a day longer. In comparison I get 3% cash back by using my credit card. 100x more.
You've got a lot of writing on your website about the merits of investment. That's fine I guess but is unrelated to the function of your business. It is also weird to tell people "just don't spend money on food now and then eventually the investments you bought instead will pay for food." While this is technically true you are doing nothing to help people have money to invest today.
Also practically, what happens if I've set a no-loss rule and there is a big dip right before I buy a bunch of stuff and the price of my equities stays down. Do you just never sell and now I silently don't pay my credit card bill?