Eurail Pass includes the glacier express, (But the Swisspass also includes a few mountain railways and a couple cable cars that are not included with the eurail pass, but basicly all regular trains are included in the eurail pass) The Glacier express requires an expensive reservation but that is the same for both passes.
Check this out regarding where the eurail pass is valid https://www.interrail.eu/content/dam/_new-structure/doc/res/sbb_validity_map_2026.pdf
As you travel multple countries the eurail global makes sense (And if you travel a lot in switzerland its usually cheaper then regular tickets)