I could do a lot with $150k but to use it on anything other than product and sales would be foolish.
At this stage in the game there is no need for an office, and any co-founder that wants to be paid should be replaced. co-founders get paid when they build a successful set of systems that offer value to everyone else. co-founders get paid last.
buying input data, testing marketing/sales channels, getting customer feedback, iterating on the beta,
The goal is to achieve some kind of proof of concept with $150k and if you could get any cash inflow going that would be great also.
I agree with Rob and other comments. I haven't heard any investor say they provide money for the earliest seed stage pre-product. They expect the entrepreneur to support their own financial needs as well as spend money as needed to develop the initial MVP. In some parts of the country, you may be able to find a technical partner who will work with you for equity. In others, you may have to pay technical people out of your own pocket (hopefully, you can negotiate a reduced rate since no startup can afford the full fee an established company would pay). As your company gains attention and notice, you will start to find it easier to attract good people who will work with you for equity.
So initially, the financial burden is on the entrepreneur. By taking this on, they demonstrate faith in their product and perseverance. This may be harder when the entrepreneur is more established in their career as they can't live in their parent's basement, but on the other hand, they have had time to build up savings over years.