It’ll be standardized soon: PEP 621: how to specify dependencies?
One thing that would assist users would be the ability to select the file. My team at Datadog isn’t using it because back when I investigated the file name was assumed to be requirements.txt at the root but ours is https://github.com/DataDog/integrations-core/blob/master/datadog_checks_base/datadog_checks/base/data/agent_requirements.in