I test my own creations on Linux with Orca (maintained at https://gitlab.gnome.org/GNOME/orca) and on Windows I rely on NVDA (downloadable freely at https://www.nvaccess.org/download/)
Thank you for carrying out testing. I should note that, unlike the probable majority of HN readers, MacOS and Linux are nowhere near as popular among blind users as Windows. MacOS has a decent market share (around 10-12 percent or so), but the number of screen reader users on Linux is almost insignificant.