I've own and use metric die nuts, a word of caution, mine generally cut/clean a little deeper than standard pressed threads. Different brands may also cut different depths, since your spigot is already galled, in preference I would buy an adjustable thread tap to carefully clean your existing threads without cutting any deeper if possible, of course that also depends on what damage and burrs there are to be removed. The galling may have happened from thread deformation due to a filter being over tightened, very easily done on aluminum spigots. Filter finishing in my opinion is very poor these days, swarf/burrs being left on the threads, and malformed threads seeming to be a common occurrence and may have also caused the initial galling. Thoroughly inspect your filter threads before using. A couple of other options for longer term repair, use of epoxy thread building materials and release agents, cleanliness is essential, multiple washing with acetone/other cleaning fluids to remove any traces of oil impregnated in the spigot is essential. As previously mentioned, the installation of a threaded bush, loctited to the existing spigot and selection of a suitable filter to replace the original, or the installation of a remote filter housing adapter, or filter spacer, locked in place, so that you are not utilizing the damaged spigot when changing filters anymore. Good Luck
EDIT: Forgot to mention the possibility of aluminum solder/weld rod to build the thread up then re-cut it, fairly low temp repair I believe. You would have to research.