Shell script runs manually, but doesn't behave as expected when started by systemd

I'm trying to get google-drive-ocamlfuse to mount on Fedora 35 Linux at startup. I've installed opam and successfully installed google-drive-ocamlfuse. Because this is on a laptop using WiFi to connect to the Internet, I created a bash script to run at startup, as per these instructions on the google-drive-ocamlfuse wiki :

#!/bin/bash

while true; do
  # check to see if there is a connection by pinging a Google server
  if ping -q -c 1 -W 1 8.8.8.8 >/dev/null; then
    # if connected, mount the drive and break the loop
    /home/myusername/.opam/default/bin/google-drive-ocamlfuse /home/myusername/GoogleDrive; break;
  else
    # if not connected, wait for one second and then check again
    sleep 1
  fi
done

I've placed the script in /usr/local/bin, though the blurb on the wiki does indeed say to put it in /home/username/bin. I see no reason why this would matter one way or the other. In /etc/systemd/system, I have a systemd service I made, mount-google-drive.service that's just supposed to run the script:

[Unit]
Description=Run shell script to launch google-drive-ocamlfuse at startup

[Service]
User=myusername
Group=myusername
ExecStart=/usr/local/bin/mount-google-drive-ocamlfuse.sh

[Install]
WantedBy=multi-user.target

If I run $ /usr/local/bin/mount-google-drive-ocamlfuse.sh manually, then the Google Drive folder mounts just fine. However, I can't seem to get the systemd service to successfully run the script at startup. I modified my ~/.bashrc file with export PATH=$PATH:$HOME/.opam/default/bin/ so as to permanently make google-drive-ocamlfuse available in my $PATH. I've run $ sudo systemctl daemon-reload, and rebooted. /usr/local/bin/mount-google-drive-ocamlfuse.sh has permissions -rwxr-xr-x. /etc/systemd/system/mount-google-drive.service has permissions -rwxr-xr-x. When I run $ sudo systemctl status mount-google-drive.service, it appears that systemd has indeed run the script, but for some reason it isn't *actually* mounting the ~/GoogleDrive folder:

$ sudo systemctl status mount-google-drive.service 
○ mount-google-drive.service - Run shell script to launch google-drive-ocamlfuse at startup
     Loaded: loaded (/etc/systemd/system/mount-google-drive.service; enabled; vendor preset: disabled)
     Active: inactive (dead) since Sun 2021-12-05 22:36:19 CST; 2min 58s ago
    Process: 1360 ExecStart=/usr/local/bin/mount-google-drive-ocamlfuse.sh (code=exited, status=0/SUCCESS)
   Main PID: 1360 (code=exited, status=0/SUCCESS)
        CPU: 67ms

Dec 05 22:36:11 fedora systemd[1] : Started Run shell script to launch google-drive-ocamlfuse at startup.
Dec 05 22:36:11 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:12 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:13 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:14 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:15 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:16 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:17 fedora mount-google-drive-ocamlfuse.sh: ping: connect: Network is unreachable
Dec 05 22:36:19 localhost-live.lan systemd[1] : mount-google-drive.service: Deactivated successfully.

To check to make sure that myusername is actually running the script, I run $ su - myusername -c 'bash /usr/local/bin/mount-google-drive-ocamlfuse.sh' and that mounts the drive perfectly, as expected. Why does systemd seem to run the script "successfully" but in reality it's not mounting the ~/GoogleDrive folder via google-drive-ocamlfuse as when I run the bash script manually?