Just have customers do pickup or charge a delivery fee and hire someone to do it. It’s not your job to have a prolonged negotiation with every customer about basic stuff like this. Also stop undercharging for your work. If you try to make everyone happy, you’ll attract customers who want to use small businesses as a doormat.

ADU is your best bet if zoned residential, though worth bearing in mind that landlording and AirBnB can come with their own headaches. Read up on relevant state law and look into what happens if someone stops paying rent.

You’re unlikely to find reputable renters for businesses. If someone has manufacturing or storage needs they usually want that to be their own space or be under contract with a commercial landlord. There are a lot of legal and insurance issues they could run into trying to use a residential property for anything business related.

Are they selling because vital employees are about to retire and they are looking for someone to hold the bag?

Sounds like a failing business

Sounds like a failing business

Immediate severance / last paycheck to ease the pain, document it, tell them it’s not working out

If this is the level of question you’re asking, then no. There’s no business plan here.

Just stay firm on price. You’re dealing with cheapskates who don’t have much money.