Thank you @mr_gibbins.
I think an implementation in RDBMS is worth exploring. After all, the page size of the PGM-index can be tuned to match the one of the media you are storing your data to (or to match the default setting of the RDBMS).
About the paradigm shift to use smaller pages, it's worth mentioning technological innovations like the Intel's Optane DC Persistent Memory, in which the access granularity is 256 bytes. I expect that similar products will be available in the near future and that new/updated RDBMS implementations will take advantage of them.