I’m fairly certain that any country has a warehouse full of weapons from other countries that they could supply if they wanted to maintain plausible deniability. Israel, like the US, Russia, China and Iran supply weapons to just about anybody. But I’d be surprised if Israel supplied easily identified material to either side as the political repercussions are not easy to work out in advance. Now, this isn’t to say some enterprising Israeli with access hasn’t made a non-government sanctioned deal.
Israel was used by the US to transfer arms to the rebels in Afghanistan. Russian arms captured from the Arabs, not identifiable as US, certainly not Israeli.