hi some news about accessibility support directly in odoo v16? some good third party tool or app ? 

Hello,
No, it is not yet WCAG compliant and the website isn't currently either. (For example above this box I am typing in now, the buttons are not labeled).
But the architecture is there, there just needs to be some tweaks in the HTML.
I really hope there is some kind of response from the core developers on this, because our company and the U.S. government can't use any system unless it follows WCAG2. This includes public schools and colleges!
So they are alienating a rather large market by not making their architecture accessible right out of the box.
If there is any question on how HTML works, I hope they contact me, because the things I've seen are really silly. For an edit box they matched the from attribute in the label to the name in the edit box. This doesn't work, the label needs an id, not the name.
And on buttons, they just need to add in the text inside either the value field or between the tags. Then they need to add in headings on each page.
So really basic and super simple stuff that can be changed in the template.

I'm sure someone could rewrite a front-end to everything, but this would be a lot of work and it would probably be easier to just make an update to the core..

This is an old thread but the topic is still relevant. I know that Odoo 14 is more WCAG-compatible than previous versions and now there may be some compatible templates out there "to be inspired of"!? :-)

If so, I'm interested!

" there is nice module for a toolbar for Accesibility for user to change page for grayscale etc" this is an overlay and it is not recommended to use it to meet WCAG criteria. 
Why : 
- if the structure of the page is wrong, it wont change anything
- if the alt on image is missing or not good, it won't change anything
- if the use of aria is wrong, it won't change anything
- if a font is use to have icon and it is not hidden from the accessibility, it won't change anything
-...

And it can make things worse : if you use awesome fonts or another one to have icones, if you force another police (i.e. : persons with dyslexia), then the font might not be ok.

As well, there are some GDPR issues we can think about :
- When people surf and click on a pathologies they have, there is a cookie installed to remember the pathology through different websites using the same tool. As well, a trigger (google analytics or other) to know on which button the user have clicked/press. So potentially, the company of the website and the provider of the tool have access to medical information about their user, and european law about GDPR is strict about sensitive datas.

Imagine a breach of security (and it happens to GAFAs) and then hackers can know who has got a discapacity?

So an overlay is a tool that help for contrast, size (what can be don't with "ctrl" + "+") but to have an accessible website, it has to be proprely coded and you need trained dev, designers, copywriters, etc.

It almost meets criteria, there is nice module for a toolbar for Accesibility for user to change page for grayscale etc. but i discovered that: tooltip, title or help tag for nav items doesn't work - which is a shame if you have linked another page that opens in new tab. Also there is no easy solution for pdf and doc hyperlinks, to meet web standards for PDF links - size and type display