Deep Cut Studio has a nice dirt track mat that comes in different materials & sizes starting at 4' x 4'. They also have a 6' dirt road with two half circles that can be trimmed for making custom curves. They have several city mats with suitable roads as well.
https://www.deepcutstudio.com/produc...-mat-gaslands/
Ramshackle Games has 1/64th weapons, armor, ork crews, and barrels & barricades
https://shop.ramshacklegames.co.uk/