Most of my "favourite" recommendations have already been made … Helios-44, 8mm fish-eye and pin-hole … almost sounds like the inventory of one of my camera bags
Add to that, a Meyer-Optik 30mm Lydith, with it's lovely "water-colour-like" bokeh … not one of the "new improved" versions, but an original screw-fit … possibly also available with a Pentacon logo. Just make sure it's a 30mm, not 29mm or 28mm - they had quite a choice of lenses for those Praktica cameras! There's nothing wrong with the others, but they don't render like a Lydith
Enjoy