Many solitaire games will not give you an unsolvable puzzle to play. I think freecell only had one (by accident)
Can't remember if I saw it on HN or searched for it, but you can search for the hardest solvable freecell games. I drove myself partially insane trying to solve one. Only got about halfway before I caved
(If you don't have access to windows you can run one of those web based windows desktop lookalikes written in JS).
Microsoft Solitaire (Klondike) frequently gives you unsolvable hands, especially if you're using Draw-3.
FreeCell "is fundamentally different from most solitaire games in that very few deals are unsolvable" (https://en.wikipedia.org/wiki/FreeCell) i.e. most solitaire games deals are unsolvable.
As you said, Microsoft FreeCell does only deal one unsolvable puzzle as standard (#11982 out of 32000) https://www.solitairelaboratory.com/fcfaq.html