To keep the topic short, please comment on the situation where a lay missionary comes to make an appeal for volunteers or financial support. The person wanted to speak after the homily in a Sunday Mass; I said that they had to wait until the Prayer after Communion. My reasoning is that according to Redemptionis Sacramentum, the Church does not make a provision for a second speaker after the homily… Was I wrong?
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Here’s a related post, though I admit it does not directly answer your question: https://paulturner.org/announcements-3/
I’ve also pointed out in 416 of Let Us Pray that the rubrics do not say when to take up a second collection, and that symbolically it works best if both collections can form part of the procession of the gifts, symbols of the sacrifice that the people of God are offering on this day.
We usually have the cantor announce the purpose of the second collection just before announcing the congregational song during the preparation of the gifts. By extension, I think a lay missionary could give a talk after the universal prayer for the sake of keeping the elements of the liturgy in their best symbolic place.
Another solution could be for the ordained minister to introduce the homily and then turn it over to the lay missionary in the way that a preacher might quote another source within the framework of his homily.
But what you chose is indeed defendable from Redemptionis Sacramentum.
There’s just no good solution. We all want to help the missions and encourage our people to contribute. In the absence of clear liturgical legislation, you may arrange the pieces as you judge fit.