Unlike Java edition, Bedrock wants the resource pack to be sent in parts (https://github.com/GeyserMC/Geyser/blob/master/core/src/main/java/org/geysermc/geyser/network/UpstreamPacketHandler.java#L302-L334). Hence why you need to input the pack into Geyser's packs folder, instead of a link like on Java edition

Technically, Geyser could download a pack and place it into the packs directory itself, however, this seems out of scope for Geyser. A Geyser extension could do it, and then send the pack by listening to either the SessionLoadResourcePacks event, or the GeyserLoadResourcePacksEvent to apply it as a global pack.

Mappings, unlike resource packs, are loaded when Geyser starts up; not when each player connects (hence, why per-session-mappings arent possible). They too can be registered with extensions, but that's a different story.

What's a usecase that would benefit from a URL instead of a file if you dont mind the question?

What's a usecase that would benefit from a URL instead of a file if you dont mind the question?

For me, it will prevent from rebuilding a docker image and also gives an easier CI/CD workflow for updating the resource pack