Is it permissible to collect donations for mosques inside the mosque and next to the mihrab, while announcing the donors, if that takes a long time?

It is permissible for the Imam of the mosque or anyone else to call for donations for the benefit of the mosque or the interests of Muslims. It is also legislated to praise the donors. This is evidenced by the Prophet's (peace be upon him) request to collect money for those suffering from drought and his praise of Uthman (may Allah be pleased with him) when he donated to the Army of Hardship.