This is a really interesting initiative! It may also be worth reaching out to ETH Zuri who recently published this paper https://arxiv.org/pdf/2306.10777v2.pdf. I would be happy to discuss different measures relating to decentralization (what can be measured, how, what are the different facets (e.g. entity concentration/correlation, geographic and jurisdictional dispersion, infrastructure diversity) and you can also check out work done by rated.network (some work on network penetration and HHI) as well as @simbro’s initiative on geographic decentralization here.
I contribute to Lido DAO and would be happy to help get you guys some more details about the node operators and validators that run validators as a part of the Lido protocol. In the meantime you can check out the metrics that are aggregated and published on a quarterly basis here: Lido Validator and Node Operator Metrics (VaNOM) and more info on the relevant forum thread.