The first issue is whether you’re looking at a monochromatic (probably green) strehl measurement or polychromatic (visible spectrum) in which case the figure is invariably worse. From memory there is a detailed analysis I’ve seen suggested refractors - including APOs - cannot exceed strehl 0.95.
AFAIK you need a reflector (Newtonian) to achieve better.
Then there is this page.
https://www.telescope-optics.net/com...telescopes.htm