As a continuation to https://dinonline.org/2020/12/13/tovel-for-a-gift/ What if the person you are giving the gift to is not observant, would it be an obligation or permitted to TOVEL before gifting?
If the person you are giving the utensil to is not observant than you would be the correct thing to do, and to tovel it, however preferably you should use the utensil yourself first, and then you can even make a bracha the tefillah. Regarding lifnei iver see sources.
See Teshvos V’hanhagos 1-467 and 2-406 who say different rationale why it wouldn’t be lifnei iver, such as if the person getting the present has other utensils of the same kind, i.e. he has other cups, then it isn’t ifnei iver rather mesayeya l’yidei aveiro. Additionally, he says that there is no prohibition of mesayeya to a person who isn’t religious, (Dogul Merivava Y:D 151) because they will do the issur anyways. Additionally, he just might not use the present you are giving him. Also see Vein Lamo Michshol 3-1 other reasons why it wouldn’t be lifnei iver. Therefore, we can’t say that it is actually prohibited to give him the gift if it wasn’t toveled. however, it is definitely the preferred thing to do, so that he doesn’t end up doing an aveiro. Also see Ohel Yackov (Tevilas Keilim) ftnt. 120,122 and Likutei Aharon pg. 35, Mishpitei Hatorah (Baba Metzia) pg. 53, who all discuss whether there is an issue with selling utensils to a non- religious person, because they will use the utensil without toveling it.