Section 5.15 Building Output in CoCalc
cocalc.com 1 has all the tools you need to author with MathBook XML. You will need an upgrade from a subscription to allow Internet connectivity, but at a minimum a colleague with a paid plan can spare you one, they are plentiful and meant to be shared.
Text editor: reasonably good, partially XML syntax-aware.
git: installed (so you can clone/pull PreTeXt).
jing: installed, so you can do RELAX-NG validation.
LaTeX: installed with many additional packages.
Python: installed, necessary for
PDF viewer: handed off to your browser.
HTML viewer: get a context menu on the cloud icon in the file view, and open in a new tab or new window.
HTML server: nope. Zip up output and host elsewhere.