https://nuclear-knowledge.com/detonators.php provides more information, they are designed for fast switching, but still at vast currents re. triggered spark gaps "Typically, compact versions of these devices rate at 20-100 KV, and 50-150 kiloamps, and the triggering potential is one-half to one-third the maximum voltage. Switch current rise times last 10-100 nanoseconds. "

For krytron's specifically it says 'These devices have maximum voltage ratings from 3 to 10KV, and peak current rating of 300-3000 amps' which would have been useful for detonating the exploding-bridgewire, which requires a hefty current.

Also I believe modern versions such as the following Thyratron https://www2.l3t.com/edd/pdfs/datasheets/L4906A.pdf are used with lasers. Peak current 20,000A. Peak voltage 35kV.