But literalist is what the meme theory has to be if it interacts with matter at all.

Does it interact with matter...at all?

That may be so, but the meme idea posits that something replicates. Not that it endures, or has a beginning, middle, or end, or that it is inherited, or that it is X by Y by Z dimensions. The basic litmus test is; At whatever size, does it, when given the needed materials, make copies of itself spontaneously? This is necessary for it to give rise to natural selection.

Ideas do not make copies spontaneously, human interaction is necessary.

If an idea does not have any tangible, literal substance and exists purely in an abstract state, it can never literally copy itself. Any transfer from one person to another is still in this abstract form which is communicated from one person to another. It can be communicated through any of our senses, intellect, emotions.... We can show a physical object and people can literally copy this, yet the underlying concept of the object is what is being examined. This process is not literal and searching for direct physical evidence of one idea replicating seems impossible. We can examine the results of physical manifestation, but not the actual action/idea.