Reposting this info from my post at the Mando Mercs group.
I suppose it really depends on which level of approval you're going for.
Since there's no CRL right now, you're flying in the fog as far as complete accuracy.
Generally, you'd want to not see boot laces, so removing the bottom couple rows would work.
NONE of the following suggestions are Mercs or 501st approved, FYI.
Merrell Moab FST Ice+ could work as it was used on the Mando S2 Repaint suit for publicity photos.
Merrell Coldpack Ice+ Moc is a similar style sole, but a shorter running show style upper.
Under Armour Men's Infil OPS Gore tex boots 1287948-001 Black, These are the correct style matched by another member for screen accurate BoBF "Daimyo."
The Under Armour
Field OPS GTX boot has the EXACT same sole pattern as the screen accurate
Infil Ops boot... but it's in a light grey/off white color instead of black. The upper is different also, but the toe will be covered with a boot cap anyway. You'll just need to dye the sole or paint it with an acrylic paint perhaps?
Again, these aren't approved for "membership" since there's no approved CRL yet for BoBF/Daimyo, but they might get you close.