A very small mistake here, not a big deal, really: Stéphanie de Beauharnais was not a Leuchtenberg, as the title duke of Leuchtenberg was given to Eugène de Beauharnais and was transmitted to his descendants. As for Stéphanie, her father was Eugène's father cousin (and when Eugène was created duke of L. by the king of Bavaria, she was already married in the Baden family).
The Grimaldis are not as closely related to the other royal houses as those houses are to one another, because they are, in truth, no more than French aristocrats who became rulers by an accident of History (the survival of Monaco as an independant state), and I say that with no disrespect. Up to the 17th century, they were serving Spain, so they tended to marry Italian and Spanich noblewomen. After they began serving France, they married French noblewomen, and it must be noted that they are French since the early 18th century, when the Goyon-Matignon and then the Polignac took over Monaco and the Grimaldi name.
You can find another link to German princely families through Antoinette de Mérode, prince Albert 1st's mother here:
Pedigree for Comtesse Antoinette de Merode
You can also note that, since the 17th century, only one Monaco princess has descendants in other royal houses (if you don't count princess Florestine and the Urach family): Teresa-Maria Grimaldi, an ancestor of the houses of Austria-Este, Bourbon-Parma, Bavaria, Luxembourg, etc...
Teresa Maria Grimaldi