Coolants - What OAT is Compatible?

New to this forum, hoping someone can educate me about the variations of coolants that are available... So many variations available where there is a lack of a color mandate.

I bought a used 2022 Volvo, D13 engine, 270k miles... don't know the service history on it, but pulled a sample into a glass jar and it appears to be an orange color, maybe even a pink hue at different lighting. Talking with RDO Volvo said use a Delo ELC coolant that is pink for newer Volvo trucks. A smaller reputable truck shop said any of the pink/red/orange heavy duty ELC coolants should be fine. There's no sticker present on the reservoir and the manual doesn't state either.

I know to never mix conventional, IATs, HOATs, and elc OAT coolants; however, what about similar OAT products? The variations like nitrite free and/or phosphate free OAT, NOAT, POAT, etc. that makes it more confusing when not sure what a specific engine was designed for, and when jugs don't list the formula makeup.

Don't want to stock yet another coolant on the shelf if I don't have to...worried about if someone else around my farm is servicing a machine and puts in the wrong coolant. Already have added CNH ELC OAT and John Deere Cool-Gard for two newer agriculture machines, on top of the heavy duty conventional coolant for the older ag tractors before and during the transition to OAT. CNH coolant is Nitrite, Phos, and Silicate free on the jug and have their engines labeled with stickers to either take OAT or conventional SCAs... the John Deere might be a HOAT coolant, but haven't researched around yet.

Main questions to answer:
1) What OAT coolants "should/could" be compatible with each other?
2) What specific OAT coolant does Volvo call for the D13s? Nitrite and phosphate free?
3) Is CNH's OAT coolant be compatible?
4) Are there such a thing as OAT test strips to find out if there are certain additives/contaminates present.. or does that require to send in a sample to an analysis company?

Thanks in advance.