You are on the right track with using the Points to Volume component then assigning individual radii to each input point. You just want to make sure you have same number of radii values as your number of points (ex: if you have 10 input points you need 10 radii values).
When you downloaded Dendro there should have been a set of included example files in the zip. You can check the “dendro_lattice.gh” file in the Examples folder.
I have also posted some other more complex files for driving lattices:
