For anyone who wants to see, here are some good links to lists of what Georgists would like to target:

• A non-exhaustive catalogue of economic rent sources by u/SteelRazorBlade
• The Hidden Taxable Capacity of Land: Enough and to Spare by Mason Gaffney
• Rent: A New Framework by Silvaria Lysandra Zemaitis (expands the original Georgist idea towards land to all sorts of monopoly privilege, including network effects)

Overall, there are a lot of finite (in other words non-reproducible) resources (both natural and artificial) which create economic rent that Georgists can either recoup or deal with in other ways. Land remains the biggest, but it’s also the starting point into just how deep Georgist reforms can go.