Here is history of Modhagam - true Tamil sweet delicacy. Which predates Pillayar in Tamil lit.
The post details all legends of Indra Aaram....The crown jewel gifted by Indra to the Pandya.
“did the Pandyas posses a relic of great value which was subsequently captured by the Cholas?” There surely is a relic that the Cholas had quest for more than 50 years to conquer. But the relic was not an Idol of god special to Pandiyas. Rather it was beautiful jewel called Indra Aaram and the royal crown.