Although Texas' ERCOT is not subject to FERC regulations, there are apparently emergency DOE orders that apply to some Texas generating facilities nonetheless:
Under FPA section 202(c) during the continuance of a war in which the United States is engaged or when an emergency exists by reason of a sudden increase in the demand for electric energy, or a shortage of electric energy, or of facilities for the generation or transmission of electric energy, or of the fuel or water for generating facilities, or other causes, the Secretary of Energy may require by order temporary connections of facilities, and generation, delivery, interchange, or transmission of electricity as the Secretary determines will best meet the emergency and serve the public interest. 16 U.S.C. § 824a(c). [...]
On February 14, 2021, a 202(c) emergency order was issued to the Electric Reliability Council of Texas (ERCOT) authorizing specific electric generating units (resource list) located within the ERCOT area to operate at their maximum generation output levels due to ongoing extreme weather conditions and to preserve the reliability of bulk electric power system.
Which facilities are on that "resource list" and how much of Texas power do they (normally) supply?
I found the full text of the order, but the list of units is apparently a separate document. (One intersting bit from the text though is that ERCOT itself requested the DOE to issue the federal order.)