Agreed, the reason the tig-welded nut thing is the goto option is because it applies a significantly high amount of directed heat into the area you want to break any bond from corrosion.
Welding the nut gives a big surface area for a breaker bar, on a freshly hot/cold cycled thread.
Quite straightforward - a decent bike mechanic would do it, drilling a pilot and easy out.
You could try this guy - https://www.threaddoctorservicesltd.co.uk/