Have a theoretical/processes based question so reprex is limited to the skeleton code provided with no actual DF as this is conceptual in nature.

I am interested in a.) what is returned for the prediction of a 0 response value (as coded below) when there are multiple predictor possibilities and b.) is there a way to select the smallest value of those possibilities in-line (for multiple model runs) when doing a solver via sapply (as coded below)?

models <- DF %>% 
  summarise(spline_fun=list(splinefun(A, B)), .by = c(X,Y))

models$spline_pred_0 <- sapply(models$spline_fun, function(x) x(0))