If you can get any kind of multiscan monitor you’re usually set for computers of that era. Connectors can be handled by passive adaptors if needed, but it is actually the refresh rate that is not always supported by the common VGA CRT (specifically the 15 kHz horizontal refresh rate).
Multiscan monitors had various names depending on the manufacturer. MultiSync, DiamondTron, SyncMaster, etc… so if you can get any CRT with 15 kHz support, you’re set.