Combine multiple entities into the same device

After setting up both my ESPHome relay and AsusWRT, I noticed that the entities corresponding to the ESPhome relay from both integrations were combined into a single device:

this is a great feature as it helps to keep clutter down by avoiding duplicate devices, of which I have quite a few (usually, one entity from AsusWRT, and at least one from the device’s own integration). However, it seems like most devices are not given the same identifier automatically. Would it be possible to add a feature where you can manually combine devices in this way? Thanks!