Is it permissible for this employee to lead the Friday prayer and deliver the sermon in his company, given that there is no sheikh available from outside and he is not a dedicated student of knowledge?

It is permissible to establish Friday prayers for workers, provided its conditions are met. It is not obligatory to dedicate oneself entirely to seeking knowledge from sheikhs or graduating from Sharia colleges. Rather, one must be keen to seek knowledge during leisure time. The preacher should limit themselves to conveying what they know, for dawah (inviting to Islam) must only be based on knowledge of what the preacher is calling to. So, if one learns a religious issue, they should convey it, for Allah the Almighty says: "Say, 'This is my way; I invite to Allah with insight, I and those who follow me.'"