Hello OP,
FYI, I managed a detail business for 14yrs and machine buffed well over 12k cars alone in that period of time. I was well respected in the industry. In addition, I've been maintaining my own vehicles for over 35yrs now so I've seen a lot and have tried a lot as I still keep up with the industry.
Some of the advice you have been given is good but some is either poor or simply not necessary.
If the sap is fresh just wash the area with a microfiber towel using hot water and some car soap. The sap may clean right off. If it doesn't then trying cleaning it off with some rubbing alcohol and the microfiber towel. If that doesn't work then apply a dab of hand sanitizer on it and let it set for several minutes then remove (repeat if necessary). All the above will break down the sap and allow for easy/safe removal. If none of the above works then you can purchase and try any number of tar, bug, sap removers. Even gas or paint thinner is fine despite what folks may think or say. You spill gas on your vehicle at times when filling it up? Ever had your paint peel off from such or completely fade out, no! You just should apply wax or sealant after using any strong chemicals that's all.
I would not recommend using a clay bar nor even a fine grit clay mitt. There is nothing wrong with that but it's overkill. Clay bars and clay mitts (even fine) can lead to pain marring/dulling if you're not careful which is quite common even for pro's. It's easily corrected with polish or cleaner wax.
I would NEVER recommend using a rinse-less car wash, period! Those products were manufactured for people who have no access to water (apartments) or where water is restricted, otherwise manufacturers hype it up as being "safer" for the environment. It's always safest to rinse your car first or even foam it prior to actually washing it; because that removes or lossens a lot of dirt/dust before you even put a mitt on it. People may not see swirl marks now but they will assuredly appear with such products. A swirl light will quickly reveal it. Irrespective, it is not a safer "alternative" to traditional hand washing using quality car soaps, mitts, microfiber towels. Never use a rinse-less car wash unless you have absolutely no alternative.
God Bless,
Ralph