We may (or may not) join soon.
TrustoverIP (https://trustoverip.org/) is a grouping of organizations formed in 2020 to develop a ‘full-stack’ of standards – not just technology but also governance – for internet scale digital trust.
UCD, in contrast, is a coherent set of business, technical, organization and governance models, together with a route to scale, for developing infrastructure for User Control of Data (including identity), starting in the UK education and finance sectors.
As such, UCD can be thought of a defined and focused expedition into new territory, whereas TOIP is a collective agreement between organizations that there is a lot of exploratory work to be done, and that it is better to carry out the work collectively. UCD may well draw upon some of the work carried out by TOIP.