There were so many different signs used for ornaments in early music that this one seems to have escaped Daniel’s notice.
I suspect “Praller” is an abbreviation coined by a non-German speaker (but not necessarily by k_b!) These are not the “Pralltriller” ornament which is not included in J S Bach’s well known “table of ornaments” but is discussed at some length by C P E Bach, and which is (approximately!) an appoggiatura followed by a short trill.
In early English keyboard music it is generally considered to mean either a short or a long trill.
Single slanting lines also occur, but more rarely, and probably represent a “slide” of two rising notes before the main note.
The Bravura font doesn’t have a really good symbol for these IMO. You could also try a “grace note slash stem” https://w3c.github.io/smufl/gitbook/tables/common-ornaments.html or one of the “short oblique lines” from https://w3c.github.io/smufl/gitbook/tables/other-baroque-ornaments.html but none of them really work well.