I’ve little doubt if Israel decided to field a 30 megaton bomb, they’d have one ready to launch in a reasonable amount of time.
There’s one thing Israel has in abundance, brilliant minds who can be very focused on protecting their homes. Once the polidiots get out of the way, that is.
Yes you can field it but how can you deliver it?
Unless it was made from exotic matter such as anti-matter.
Pure fission is limited to about 500kt (this is a rough figure, if anyone has any actual data, I would appreciate a link....), and as has been previously stated the Tsar Bomba was the largest fusion bomb ever detonated at around 57 mt. Of course, it was massive, took up the entire bomb bay of a heavy bomber and was deployed via drogue parachute much like one of the “daisy cutter” bombs. Chelomei actually designed the UR-500 (aka Proton) as a massive ICBM to loft it state-wards... never deployed, obviously.