Help needed for dyslexic partner

Hi, I'm hoping this is the correct place to ask. My partner is severely dyslexic and she's trying to do some training courses for her job but the site they have to learn from has no form of text-to-speech assistance and to top it off the slides on the courses have text that cannot be highlighted to copy paste into a TTS tool.

I'm wondering if there is a tool similar to the Windows snipping tool where she can draw a box around the text she's struggling with and it will be read aloud.

I've tried Googling this but haven't come across a suitable solution. Any help or advice would be greatly appreciated.