As a primer there is an canister version of the Etch primer....
Using the same to prime my new ally bonnet....
Everything else is available except 2pack....
Like everything to do with paint is PREPERATION....
If themetal ain’t clean the rust will get thru eventually...
Mostly patch repares on a saxo so cleaned down to metal at the work area with paint out side, not looking to spray a car just needing stuff to stop rusting where i have been welding
As @steveo3002 says Jotamastic 87A brushed on will give excellent protection.
Ideally put a couple of coats on.
Only problem is it the smallest pack size is 5 litres, but very cheap for the level of protection it gives.
You don't need to overcoat it, but you can if you don't like the look.
You can get a good finish if you rub it down after it has fully cured (about a day) just make sure you don't rub it too thin or you will loose the protection.