What would the pros and cons be in general for donating land to a charity?

This is a BUSINESS, not a CHARITY.

give it to a charity like habitat for humanity. they will build a house on it for the needy people, and you can write off the entire market value from your taxes

I understand the broker's point, you're in business to make money not run a charity for broke RE operators.I doubt you find an "Investor Friendly" brokerage that will cater to those that can't really buy.

We have been asked by a neighbor if we would consider donating a stay to a charity called WellRoot.

If you find yourself frequently giving to charities, then you might adopt a tenant who is a charity case and you’ll be better off (less guilt and drama) to invest in stocks or multifamily real estate and don’t buy single family homes to rent.

They are a business not a charity. 

on a side note agreed not so easy to be a charity and do the right thing.. hoops.. to jump through and lots of competition for donations.. we have done it with zero expense for marketing its all grass roots.. and many of our BP members have generously contributed..  

And being a landlord is business.. just like when everyone gets on her and says they are not running a charity they are running a business.. well there you go protect your business.. cant have it both ways.land lording no different.. as a property owner or landlord its incumbent on that owner to plan for how they are going to maneuver through tough times. 

I would not keep the rent the same or raise it slowly, you are investing not running a charity (covid means you might not do it right away, but still would not be a multi-year proposition)