I also found some other hints in this Stata user list, like using gllamm, or implementing models suggested by
Kyriazidou, E. (1997). Estimation of a Panel Data Sample Selection Model.
Econometrica. 65 (6), pp. 1335-1364.
Wooldridge, J. (1995). Selection Corrections for Panel Data Models under
Conditional Mean Independence Assumptions. Journal of Econometrics. 68, pp.
However, it is difficult for me to apply theoretical models in Stata. Hence, my second question is whether, since the last posts, there are examples for the commands of selection models using gllamm, Kyriazidou's or Wooldridge model in Stata.