Unless ERCOT ramps up hiring via H1-B visa process, I don't see how they can fill this gap - "ERCOT’s job board showed 65 job openings on Jan. 13. Twenty-five of them are for engineers. Nineteen are information and technology jobs."
"The H-1B program allows employers in the United States to temporarily employ foreign workers in occupations that require the theoretical and practical application of a body of highly specialized knowledge and a bachelor's degree or higher in the specific specialty, or its equivalent." https://www.uscis.gov/tools/reports-and-studies/h-1b-employer-data-hub
Recent stats indicate RTOs are not hiring engineers via H-1B program, except for NYISO in 2021. This trend could explain the staffing shortages at these RTOs.