Here is a valuable webpage for anyone who might be inclined to host Ukranian refugees. It is not so much an 'organization' as it is a well-used repository of homes and families who offer to take in these people. The refugees themselves, and NGO's are using this site to locate available abode. If you wish to host, just go jere and enter your data. The site is self-explanatory and quite intuitive.
https://www.ukrainetakeshelter.com/