Is it permissible to advertise and promote halal meat inside the mosque after Friday prayer, or to place an advertisement for it on its outer door, with the aim of providing it to Muslims and collecting money for that purpose?

There is no harm in announcing matters of obedience inside the mosque. As for worldly matters, such as trade, it is not permissible to announce them inside it; rather, it should be done outside, on the doors or external walls. It is forbidden to advertise profitable commercial matters inside the mosque. However, charitable projects that are not profit-oriented may be announced concisely. The mosque should be avoided from being made a place for commercial meetings or collecting money.