I used to spray undercoating for Auto One stores.
IMO I would never use any product like that. All it does is close the factory drain holes and make a mess of the underside of the vehicle.
Just keep it clean by hitting the drive through car wash or spray the underside a couple times month during the salt season and you will be fine.
I have a 2000 GMC that I bought new and it has 160K on the clock. Aside from the factory frame coating flaking off, it still looks great

Undercoating is overrated, especially on the metals used today. Save you money.