I’m assuming your up! is a 3 door?
The Golf’s sill is approx 550mm long between where it starts to curve upwards, it’s pretty close though. Maybe a 5 door up! GTI sill protector would be better length wise.
The 35mm would fit fine *but* the Golf has a slight crease running the full length of that part of the sill meaning it’s almost dual level. If the tape on the back of the sill trim was really thick it would be fine but if it was just thin double sided sticky tape (like carpet tape) then there would be issues. In other words it would be a bit of a bodge.