I performed a quick test of the 'devel' branch both on a Debian 12 as well as a Fedora 41 VM w/o any issues.
I've done quick tests on Windows 11/Python 3.12 & 3.13, EndeavorOS/Python 3.13, and Linux Mint/Python 3.12. All worked except on EndeavorOS. EndeavorOS had the problem we've been seeing with the PyQtWebEngine v 3.9.0 package. The workaround of setting an environmental variable didn't work (export QTWEBENGINE_CHROMIUM_FLAGS=--disable-gpu) and I had to downgrade to 3.8. Of course, this doesn't have anything to do with this version of Leo. It's a Qt issue.