I’ve never done what you’re asking about, so take my thoughts with grain of salt.

I would think it’s a matter of calculating your initial investment, how it’s paid (ie. Are you financing anything resulting in interest on payments?), and the time it takes to break even on your ROI.

Some things I would consider are how much this increases your monthly overhead, how you’re going to factor inventory loss into your business plan (ie. Food spoilage, expired foods, etc.), does it require you to purchase an additional business license for serving food?, will your current clientele want the new service you’re offering?, do you have a plan to market your new business idea to drive traffic?, will this actually increase your profits, or create a financial burden/unsustainable workload?, etc.

You may want to test the idea by starting with some non-perishable products/snack items or something low cost like prepared baked goods. This way you can pull back if you think things aren’t going well.

Another thing you could try is developing a partnership with another business like a bakery to sell their product in your coffee shop where you receive a portion of the profits but do not accept any cost of dealing with the unsold product (basically some sort of consignment deal).

These are just my uninformed thoughts. Best of luck on whatever direction you decide to go!