I chose to go the COPR & additional repos route. I had a pretty rough experience with toolbox: containers randomly having launch errors & failing to start, GUI errors & missing components of installed apps, etc.
In containers I am installing only packages that are writing to immutable directories (e.g. /usr & /opt) in runtime. To be fair, would be nicer of texlive developers to patch it to write only in mutable directories, like /etc, but we have what we have for now.