Nobody is going to know this.

You will have to purchase the Hansgrohe, and see if the pieces fit. Most online places have a 30 day return policy - be sure to check for restocking fees.

Your wall elbow and the bar itself are no problem. The only issue is whether the Grohe handheld shower will fit in the receptacle on the bar. Maybe you can go to a plumbing show room and just try it.
If it's not too late to return what you already bought, you can buy the pieces separately. Buy your Grohe valve/trim and buy the elbow, bar, hose, handheld shower and tub spout from Hansgrohe.
By the way, I used Grohe valve/trim and Hansgrohe wall bar/elbow/handheld in my new shower, and I like them very much. The brushed nickel finishes look fine together.
Good luck!

We have a mix of Grohe and Hansgrohe in our shower. The only issue arose when the Hansgrohe hose didn't fit snugly with the Grohe handheld shower head and it leaked. Contractor remedied this by using a different size washer in the connector. No issues after that.

I have about 90 days to return the Grohe stuff no charge so that is good news. I guess wall Hansgrohe wall elbow should be ok but matching Grohe shower head to Hansgrohe hose/bar might be tricky? I might get a Hansgrohe hand shower too then just in case. Thanks all!!