I THINK, but do not know, NO rice wafers, because it has to be wheaten bread.
But the question was what is the celiac person missing? Anything? That would help evaluate the gravity of withholding the chalice. I agree that there’s a difference.
(Incidentally your “big difference” is a fine example of the REALITY of what I’m calling “ideas”.)
“shot glasses” (as we disrespectfully called them at my Episcopal seminary), I don’t think there would be an objection in principle. I don’t know how “drop dead do not ever break this rule” this particular rule is, but I THINK there’s a rule that the inner surface of the bread container (paten or ciborium) or the wine vessel (chalice) should be gold, ceteris paribus.
From the website of the USCCB:
Can a priest or bishop change this teaching and consecrate a host made of rice??
No. It is impossible to consecrate a host made of something other than wheat and water. No priest or bishop can change this longstanding teaching of the Catholic Church. A little over a year ago, Cardinal Joseph Ratzinger, Prefect of the Congregation for the Doctrine of the Faith, once again took up this question on behalf of the Holy Father when he wrote: “Hosts that are completely gluten-free are invalid matter for the celebration of the Eucharist.”2 Cardinal Joseph Ratzinger, circular letter to the Presidents of Conferences of Bishops, July 24, 2003 (Prot. 89/78-174/98) in BCL Newsletter, November 2003 (Vol. XXXIX), p. 45.
The Jesuits raised this question for reasons of inculturation when they entered China (or was it Japan?) in the 1600s, they got the same answer then.