Forget to mention it earlier, but have you consider using existing statistic/analytic tool such as Statoshi[1-2]? You may get some inspiration of what you could analyze further.
OP_RETURN is just the standard way of adding a small arbitrary data to the bitcoin blockchain, which is why they call it "nulldata".
For additional reference, OP_RETURN used by OmniLayer and Runes protocol to create token. OmniLayer was mainly used for USDT which AFAIK no longer supported by Tether, while Runes is about NFT/token.
[1]
https://github.com/jlopp/statoshi[2]
https://statoshi.info