Herelink is a RC, telemetry, and video transmission all-in-one. They are all packed into a single protocol in 2.4GHz ISM. It doesn’t matter whether you are using all or partial of its capabilities. The system communicates in 2.4GHz.
So, if any other system is transmitting signal in the same band, they are going to collide and interfere each other. In that case, we cannot guarantee Herelink to be working properly as its spec.
However, there is a frequency hopping feature in Herelink, which switches the frequency within 2.4GHz band. Therefore, it is possible that your other 2.4GHz system has a narrow enough bandwidth, and Herelink manage to avoid it.
Base on different scenario, equipment, and other factors, the interference between 2 can be variate greatly.
Is Herelink still workable if there are other 2.4GHz devices in range? Probably yes.
Hence, can it still maintain the same maximum range? Probably not.
Hence, how much of its range would be reduced? We can’t tell.
You can still use the system in that way but it is not recommended. You should understand the risk and know what exactly you are doing.