As far as what I managed to derive frm Google the Guatemalan chachal necklace GV is wearing in the old photo is rather common folk jewelry item, esp. nowadays. Also, the evidence that can be derived from recent images is weak simply because if some blogger or a celebrity is seen wearing a particular necklace it does not necessarily mean that the person owns the piece or even knows what it is but is just doing advertising for a designer or a retailer.

Therefore the connection probably not in the shape of chachal or who else wearing it, but in the origin of this chachal necklace type = Guatemala.

Now, Vanderbilt University Medical center runs several projects in Guatemala, from which the "Manna project" sounds fishy by its name, whereas the other projects seem to involve Guatemalan citizens from the most vulnerable layers of society. From their web page:

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Vanderbilt Initiatives in Guatemala

The Vanderbilt Initiatives in Guatemala include a number of inter-related health projects including:

The Moore Center for Pediatric Surgery which provides much needed health care to disadvantaged children.

The Manna Project which provides service learning opportunities for students and recent graduates

Primeros Pasos which is a rural health clinic that serves as a base for service-learning trips, the Emphasis Program, and Project Pyramid. Primeros Pasos also works with the Vanderbilt School of Nursing, giving nursing students the opportunity to work with local midwives at the clinic.

the VISAGE course which is a collaboration between Medicine, Health and Society and CLAS and brings students to Guatemala for the summer to work on various projects

Mani + which is a collaborative project founded by Edward Fischer with support from the Vanderbilt Institute for Global Health and the Shalom Foundation to combat childhood malnutrition to combat childhood malnutrition.

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Further down the page, it may of course be unintentional, but the association between business model and pyramid is bit weird:

"… for business school students to develop business models for projects in Guatemala through Project Pyramid."

SOURCE: https://www.vumc.org/global-health/vanderbilt-initiatives-guatemala