Installing a BrainVisa developer environment is now done using Pixi. It consists in cloning the soma-env repository from github, starting a pixi shell in it, then running the bv_maker command. The full instructions are there on the github repository: https://github.com/brainvisa/soma-env

Note that the new stabilized branches are the 6.0 set of branches, which should be preferred (to main/master) unless reworking major changes in the libraries.