No there is no such thing as a pro bono lawyer for this type of case. If you can't afford an attorney you have a right to have a Public Defender appointed at your first court appearance. There is no charge for the services of the PD but s/he is not a pro bono lawyer in the traditional sense.
A PC 211 is a very serious charge: theft through force or fear. It carries state prison time and a strike. You should not talk to anyone except your PD about the facts of your case.
PC 211 charges are very serious offenses that carry very serious penalties, including a possible "strike" if convicted. For a case of this magnitude, it is highly unlikely that you will find an attorney to take this case pro bono. However, if you cannot afford an attorney the court will appoint a public defender to represent you. Good luck.
As you've read from the prior answers, you're unlikely to find an attorney to take this case on a pro bono basis. If you truly cannot afford an attorney, you are entitled to representation by an appointed attorney.
You're looking at a strike for what's known as an "Estes" robbery - a theft that turns into a robbery by the use of force when store security gets involved.
There can be defenses to this - either to the elements of robbery and/or trying to reduce this to something less harsh.