Smile
you are most welcome
“You only have a Mitzva to buy from a Yid if the Yid wants your business.”
The yid wants your business. Don’t blame tyour misplaced “chumra” on him He looks to his Rav for guidance and follows all the instructions his Rav gives him.
If thats not good enough for you as you said “The “machmirim” also have the option to choose where they want to shop.” this is true from a legal standpoint although perhaps not halachik.
you say “”However, there are some Yidden that do mind buying Chometz that was sold.””
There are all sorts of yidden some kep Shabbos some don’t
Its not too late to do teshuva become a real machmir without the quotes. buy from yidden