The paper Leendertse, Schrijvers and Stam (2022) below gives an academic presentation and description of the European Entrepreneurial Ecosystem Index 2022. It covers 273 regions across Europe at the NUTS-2 level.
Leendertse, J., Schrijvers, M. & Stam, E. (2022) Measure twice, cut once. Entrepreneurial Ecosystem Metrics. Research Policy 51.9 https://doi.org/10.1016/j.respol.2021.104336
The Entrepreneurial Ecosystem Index Europe 2022 data is also available for download.