Does anyone here has some ideas : I have a customer that will keep his EDI systems and we need to do integration with D365F&O.
what strategies would you recommend? They have several systems: SPS commerce and Itrade
Do you think using a 3rd party ISV is a good idea ? otherwise which other tools are good?
ISVs are nice, because it's nice to be able to hand that stuff off, but they're usually expensive.
Like Martin said, you could always build something yourself, but there's lots of moving parts to deal with. Getting data into and out of D365 is pretty straightforward using data entities, but dealing with error handling and mapping is something you usually need another tool like Logic Apps or something to deal with.