Eufy battery doorbell: Extra chime

We have an Eufy battery doorbell with a homebase. The chime however can’t be heard on the first and second floor. What device can I add to create an extra chime?

I’m in the same boat and managed to buy an additional Chime (not sold outside of the USA), in the hope to be able to connect it.
I know the Chime is for the wired doorbell, but I did wire my battery version of the doorbell in the hope that would count.
Unfortunately I don’t see an option to add it to my setup :frowning: