what are you hoping to accomplish by setting a channel in a development build? as far as i know, there is never a need to include a channel in a development build, since it loads development servers, or it can load the latest update on any channel or a specific update with an update id.
In fact, the goal is to be able to test quickly in a preproduction environnement in a stabilisation phase: in dev client it’s very easy to load a new update on a channel (once logged it’s listed in extensions tab) and make comparisons. So we make many eas update --branch ... but env variables are sometimes forgotten so we loose time (and there is a confusion with eas build where env variables are read in eas.json so --profile is sufficient to have good configuration). In the past I have used releaseChannel to determine which configuration the app must use according to releaseChannel, I wanted to do the same thing : even if you can override with env vars, by default there is a configuration by environnement in the code according to the channel (production, preproduction …)