I think it is important to also see the Christological significance of this topic in that "the Lord" who opened the heart of Lydia (and of all believers) in Acts 16:14 is the Lord Jesus. Luke uses this same Greek word (dianoigō) in reference to Him in Luke 24:45 - He opened their minds/understanding of the Scriptures.
And "the Lord" to whom Paul prayed to direct their hearts also refers to the Lord Jesus in 2 Thessalonians 3:5 (cf. 1 Thessalonians 3:11; 1 Chronicles 29:18).
And "the Lord" to whom Paul prayed to direct their hearts also refers to the Lord Jesus in 2 Thessalonians 3:5 (cf. 1 Thessalonians 3:11; 1 Chronicles 29:18).