Brought a very cheap pair of prescription glasses [ £13.33] and made a plate to hold the lenses in place. Easy pop the lenses out of the old frames.
https://www.printables.com/model/496116-betafpv-vr03-fpv-goggles-lenses-holder
Plate to hold lenses inside the BetaFPV VR03 FPV goggles as the goggles are smaller than all tested glasses frames. (Needed size is ~110mm)
Print two plates - with the bed side of the pieces facing inwards. Needed as the is a chamber on the top side.
Screw together is 6 2.5mm nut and bolts. Place in goggles.
Note my FreeCAD could be improved but it works. Blue-tac is another option.