Are there any actual knight-errants? That is, knights that quested or wandered in pursuit of glory and honor, similar to Amadis of Gaul and Sir Gawain from the romances.
Although they are less poor than typically depicted and did not spend their whole life “questing”, some noblemen did have a hobby of participation in “crusades” on a regular basis (which weren’t all to the Holy Land,) more out of a search of glory (and especially love of war) than of a search for power or money.
And a lot of them were not the pledged vassal of the leader of the expedition but nonetheless fought, so the “wandering” part of the tale holds true, at least.
Well, Sir Ulrich von Lichtenstein was a knight, wandered [and purportedly fought several seasons of jousts dressed in drag, and wrote poetry.