I am looking for Implementing One-to-One messaging through Salesforce that can be a great way to enhance communication and accessibility to visually impaired non profit organization, can anyone suggest third-party apps please.?

To assess user-friendliness for visually impaired people, it's essential to consider the accessibility features of each app. I am Looking for features such as compatibility with screen readers, keyboard navigation options, high contrast themes, and adjustable font sizes. I also want to consider the cost implications, any recommended websites of the respective apps where I can review their pricing models is appreciated. Any provider offering free versions or trial periods? Any subscription fees based on the number of users or features required. Additionally, any app providers who can offer special nonprofit discounts.

Thank you.