I turned my phone off and then turned it back on after several hours, which caused the system time to become unsynchronized. The incorrect system time may be the reason I'm unable to establish a VPN (WG+VMESS obf) connection. This behavior seems similar to TLS handshake errors that occur when trying to access a website with an incorrect system time. I suspect the root cause is that the time synchronization service in GOS (time.grapheneos.org) is routed through the VPN, and since the VPN app isn't functioning, it creates a dead end.
According to the docs https://grapheneos.org/faq
Qualcomm Snapdragon SoC devices also fetch time via NTP for xtra-daemon instead of using potentially incorrect OS time. We use time.grapheneos.org when using the default GrapheneOS PSDS servers or the standard time.xtracloud.net when using Qualcomm's servers. Stock Pixel OS uses time.google.com but we follow Qualcomm's standard settings to match other devices and to avoid the incompatible leap second handling. These connections all go through the Owner VPN so it isn't a real world fingerprinting issue.
A possible workaround is to connect using the OpenVPN protocol, allow the system time to synchronize, and then switch to your preferred protocol for the connection.