wget -O- https://raw.githubusercontent.com/rootmos/texhelp/refs/heads/master/texhelp | sh -s -- -i

or clone the repository and

./texhelp -i

installs an isolated TeX Live system in .texhelp (or $TEXHELP_DESTDIR), which can be activated à la Python's venv:

. .texhelp/activate

which brings tlmgr, pdflatex and friends to the party.