participate in Medicaid or CHIP, which may include education, training, recruitment, and retention of such providers, with a focus on improving the capacity of the mental health and substance use disorder care workforce in rural and underserved areas by increasing the number, type, and capacity of providers. Such guidance shall include, but not be limited to— (1) best practices from States that have used Medicaid or CHIP waivers and authorities under titles XI, XIX, and XXI of such Act ( 42 U.S.C. 1301 et seq. , 1396 et seq., 1397aa et seq.) for such purposes