Yes, you can cross reference the filters. Most auto-parts stores will have the cross reference guide. You can also find a cross reference guide on the auto-parts stores website.
Anyplace that sells filters can tell you the cross reference on the filters they sell if you have the Briggs #. You have to go there anyway to buy the filter.
PZ0019 is not in the Fram Filters cross reference guide.
Purolator 60362 is not in the FRam Filters cross reference guide.
Guardian OG5894 is not in the Fram Filters cross reference guide.
One option is fram PH 4386
look up WIX Filters
wix 51334
PF4967
You do not have to use a Denso oil filter, you can use any brand filter you want. Go to any auto parts store and they will cross-refernce your Onan filter to another brand. Purolator, Wix, & Bosch make excellent filters. I looked this filter up on the Purolator cross-reference chart and came up with no results. Is it possible you're using the wrong numbers.
0D9723
The Fram Fiters cross reference guide does not list OG5894.
Yes, but I do not recommend Fram filters as they are inferior in quality. Purchased a Purolator filter that will replace your Briggs filter. Any auto parts store that sells Purolator filters can cross-reference your Briggs filter.