The Israeli military is arming and training the neo-nazi militias in Ukraine. There are even Orthodox Jews who joined the Azov neo-nazi militias to defend Ukraine. Sometimes it can be complicated.
Israel sells weapons to anyone, it's just business.
As for the "orthodox jews fighting alongside nazis", that is just an unfounded claim, without any evidence other than double hearsay in a third-rate newspaper.
Orthodox jews often don't serve even in Israel (inb4: yes, yes, ulta-orthodox, etc etc, but still, and yeshiva students are still exempt).
I'd like to see stronger evidence than hearsay for this extraordinary claim, does it exist?
https://www.timesofisrael.com/ukrainian-jews-push-back-again...
https://www.haaretz.com/israel-news/rights-groups-demand-isr...