The unclear case of usability widgets on your website

There are lots of tools/addons/widgets you can add to your website, with the intent of improving usability or accessibility. You can also build multiple versions and variations, to cater to different people and needs (or for compliance).

Should you or shouldn't you do this?

The downsides

I've been quite conflicted about this. Let's start with the downsides first.
My background is as a developer. I also like to believe I have a sense for business. Doing anything twice feels incredibly wasteful.
For example: you're building a low contrast website with brand colors. You offer a second version with a higher contrast (usually for accessibility).
This would mean you basically run two websites. Maintenance, security, testing, accessibility... pretty much everything (except for checking contrast) needs to be done twice. That does not appeal to me. At all.
I don't find it very inclusive either. You have a special website for "special people", or something alike? The inclusive solution (in my opinion) would be to have one website for everybody. And if that website is good, then everybody can benefit from a nice and proper contrast.
So that's:

• possible superfluous work,
• lack of inclusion and
• not benefitting all visitors.

Another point that aligns with the (lack of) inclusion is having to declare a need. As a visitor it's like you have to say "I have a disability" because you need to make a conscious choice to use a different version of the website. It can be rather confrontational. Experiences like these are quite negative for me.
Also good to know is that people with disabilities often have lots of tooling available. They know their limits better than you. Build a proper accessible website, and their tools will be able to deal with it.

The upsides

But then there are some upsides as well. The first can be rather commercial. There's value in communicating that you care about the user experience. By putting up a button that reads a page out loud, you communicate a positive message.
You're also adding value for people who don't consider themselves as having a disability, or don't want to confirm or acknowledge such. Let's say you're having trouble reading a website, but you don't want to call yourself dyslexic. You could use the button already present. You're not required acknowledge a disability, and to learn about tooling. It's already present.
And finally, assuming your addition doesn't exclude anybody, then there's no harm in adding it right? If your addition is beneficial to some, but doesn't exclude anybody else. Sounds like it's valid to try it out then!
Common customizations in this category are typography, contrast and reading text out loud.

Where does that leave us?

I wouldn't depend on a widget, alternative versions or anything alike to enable access. Create the best experience you can, and let everybody enjoy it. If you can improve the experience for some, while not harming others, I lean towards doing so.