We don't find ssistitve tecnoogy theory. We are using the Inclusion paradigm of Ferdman [Ferdman, B. M. (2014). The practice of inclusion in diverse organizations: Toward a systemic and inclusive framework. In B. M. Ferdman & B. R. Deane (Eds.), Diversity at work: The practice of inclusion (pp. 3–54). Jossey-Bass/Wiley. https://doi.org/10.1002/9781118764282.ch1
Ferdman, B. M. (2017) Paradoxes of inclusion: Understanding and managing the tensions of diversity and multiculturalism. The Journal of Applied Behavioral Science, 53(2),235-263.] to work
My doctoral dissertation, The Relationship between Assistive Technology State Standards for Teachers, Assistive Technology Implementation, and Student Performance in the Context of Evidence-based Practice (listed on ResearchGate under my name) use an assistive technology questionnaire (not standardized, but vetted). Perhaps it can be helpful to you.