`rosdep install` fails with conda-related errors after following Pixi install instructions

I've followed the getting-started instructions here: https://robostack.github.io/GettingStarted.html#__tabbed_1_2

I was able to get roscore + rviz working, but when I tried to import dependencies for the package I'm working on, I get this error:

(robostack:noetic) bash-3.2$ rosdep install --from-paths src --ignore-src -r -y

ERROR: Rosdep experienced an internal error.
Please go to the rosdep page [1] and file a bug report with the message below.
[1] : http://www.ros.org/wiki/rosdep

rosdep version: 0.26.0

Bad installer [conda]: None of micromamba, mamba, conda was found.

Do I also need to install conda if I'm using pixi?

I'm running on MacOS 15.4.1, and have run the following commands:

curl -fsSL https://pixi.sh/install.sh | bash
pixi init robostack
cd robostack
vim pixi.toml # copy over content from tutorial
pixi install
pixi shell -e noetic
mkdir -p catkin_ws/src; cd catkin_ws/src
git clone git@gitlab.com:[my_package]
pixi add vcstool
vcs import --input [my_package]/[my_package].repos
rosdep install --from-paths src --ignore-src -r -y

Possibly related: I get warnings about missing install/setup.bash:

totten:robostack lindzey$ pixi shell -e noetic
 WARN Could not find activation scripts: /Users/lindzey/Documents/RSAmanip/robostack/install/setup.bash

Start with the GettingStarted.html Pixi instructions and reproduce the commands in the issue, especially rosdep install --from-paths src --ignore-src -r -y. Check the copied pixi.toml and the reported missing install/setup.bash warning. Done means determining whether conda is required with Pixi and correcting the instructions or documenting the required setup.