Perhaps some topic drift, or feature bloat is occurring here…
OP wants something that is easy to use, presumably easy to get, relatively cheap, with durable protection the primary goal, not looks. For a biannual routine that isn't a hobby.
No doubt, prep is key to getting the best results with any coating job, whether paint or some sort of other protective coating, and the manufacturers wouldn't include such recommendations in their instructions, even for easy-to-use products, if that wasn't the case.
Being in the same boat, and having switched to GG 3/1 as my primary product, for the initial process, I've used Adam's Strip Wash (both can be had from Amazon) for prep, clayed the surface, and then the initial coat, +1 a day later as specified, and have no complaints about the results, or the durability, which is even better for a garaged vehicle.
Once that initial hump is cleared, these products are so easy to use, refreshing them is a trivial task, which can result in additional effectiveness.