Hi jimmy! Yep, invariably the ask always ends up to be 2-way syncing. :-/
Fwiw realistically I think these things are generally best written as custom software anyway, b/c things like identity (of entities/mapping ids correctly across both systems), the inevitable field mapping, etc. always come up, and with custom software I can write tests for all of them. :-)
Two-way is definitely more convenient. Custom could be a good approach, but could get difficult to maintain due corner cases or as schemas change from either side. I'd be curious to know how you end up solving for this! Good luck!
Fwiw realistically I think these things are generally best written as custom software anyway, b/c things like identity (of entities/mapping ids correctly across both systems), the inevitable field mapping, etc. always come up, and with custom software I can write tests for all of them. :-)