A revised version of @NamanMadharia 's post to avoid headers and simplify it a bit:
conda list | awk '!/^#/ && NF {print $1}' | xargs
This doesn't use a conda property, but the conda list output comes in columns and can be manipulated with the above command easily enough.
conda list (OP already describes what this one does)| is the 'pipe' command and sends the output of a previous command as input for the next.awk "is a utility that enables a programmer to write tiny programs [and] is mostly used for pattern scanning and processing."[1]!/^#/ ignores any comment lines in the output eg the column headers.&& NF makes sure the line has at least one field of content, ignoring empty lines.{print $1} prints the content of the line's first column.xargs prints the outputs of the previous command (which is run on every line) as one line seperated by spaces.