The boots are German Army nobelbeckers.
Ideally there should be an adjustment strap at the top.
These are fairly easy to source online.
Knobelbecher Bundeswehr jackboots are good for this.
Knobelbecher Bundesmarine jackboots are very similar, but have holes at the top of the boot, and have textured leather, and can be substituted but the holes will need filling with leather putty.
Knobelbecher Marschstiefel jackboots are generally slightly higher without the adjustment strap, and have a metal horseshoe and studs on the sole, so aren’t recommended.
Knobelbecher Wachmatallion (Guards) boots are exactly the same as the Bundeswehr boots, but don’t have the top adjustment strap, and have a metal horseshoe heel. These are clearable.
Knobelbecher Seestiefel (Sea boots) boots are similar to the Bundeswehr jackboots, but have zips and are fur lined. The zip makes them not suitable for clearance.
Finnish M34 boots are generally straight legged without the adjustment strap, and are too tall for clearance.
Bundeswehr means Armed Forces
Bundesmarine means Federal Navy