Would it be possible for WMUK to join the government's sponsorship scheme as a registered UK charity and provide organizational and practical help and probably a very modest amount of funding for someone fleeing the war in the Ukraine to stay in London? It's likely that funding will be available from several sources if requested, so WMUK may not need to directly fund anything apart from some coordination time from an employee and of course interested volunteers.
Talking to others that have sponsored political refugees in the past, such as religious groups, there is an expectation that you have a connection to the sponsored refugee, and it would seem appropriate to seek to sponsor an academic or librarian, or even a past Wikipedia volunteer who is unable to use the other routes as they don't have existing close family living in the UK.
Could the trustees have a discussion about whether this is reasonable and allowable under the "libraries" and open knowledge scope of the charity and the agreement with the Wikimedia Foundation? If it's not reasonable to take direct action, the trustees may have other ideas of how WMUK can be seen to help.
Reference: https://www.gov.uk/guidance/local-sponsorship-scheme-for-ukraine
Thanks, Lane