The current Electrs networking capacities/exposed interfaces are currently limited to what they are, but this will eventually change as we move into StartOS v036 and v040.
You can rig something up yourself until then by using this guide: [DIY] Exposing electrs and bitcoind over LAN in StartOS 0.3
For Fulcrum, yes, but we’re waiting for them to fix a bug and release the fix in v2.0. Currently if the initial DB build is interrupted the entire DB gets corrupted. So until they fix that bug, it’s a nonstarter for us.