Oooh, there's lots of options. A few that might be of interest:

Reverend William Hechler: An associate of Herzl, Hechler (very much unlike Herzl) was a bit of a religious nut. He was, however, extremely well connected in both Germany and the UK. Within a couple months of meeting Herzl, Hechler gets Herzl a meeting with the Grand Duke of Baden and is putting in a good word with the Kaiser. In short, he plays no small part in making this happen.

The Blackstone Memorial: organized by another Christian religious Zionist, reverend William Blackstone, the Blackstone memorial nonetheless garnered the support of a large number of incredibly prominent gentiles (e.g. J.P. Morgan) and did so five years before Herzl publishes Der Judenstaat.

Then it might be worthwhile looking looking at the British cabinet that that was associated with the drafting and issuing of the Balfour Declaration. The motivations of men like Balfour and Lloyd-George are interesting and complicated and were in some instances outright anti-Semitic, but anti-Semitic Zionism was very much a thing (just as Jewish anti-Zionism was very much a thing.)

You might also be interested in the emergence of American support for Zionism. The Lodge-Fish resolutions back the Balfour declaration in '22. Again, if you track down the congressional transcripts whats interesting in some ways are the contradictions involved in the motivations. The senate was fully aware at this point that they were going to pass immigration restriction. This was, "fig leaf" would be too light, but opening the door to Palestine for Eastern European Jews facing pogroms sure made it a lot easier on the consciences of senators looking to close the door to America.