That's a good question, but the answer needs to come from Opera.
The Nokia 216 is a 2016 feature phone that came with Opera Mini preinstalled. The phone's built in apps, including Opera Mini, are based on MediaTek's MAUI Runtime Environment, not Java ME or Symbian. I believe that Opera had a contract with Nokia or Microsoft to develop an MRE-based version of Opera Mini for these phones.
Perhaps you could reach out to Opera Mini infrastructure team and ask if MRE Opera Mini is still supported.
I have seen a line of new budget Nomi phones, with at least of 32 mb of internal memory and 32 mb of operative memory (despite I ask here what operative memory as well as internal consumes opera-mini 4.5). I think it should be enough?
Indeed I fear that opera mini 4.5 stopped of production - as I do not see any answer here?!
Although the 2g traffic speed should be some bottleneck, as well I do not know should these Nomi phones support
java jar apps??