I have the latest Cisco IOS XR (7.x), and I am trying to find a way to run a bash or python script stored on the router on every reload. Is there any ways to do this?
Not Bash or Python necessarily, but EEM (Embedded Event Manager) is meant for this purpose. You use it to do various things (such as run scripts) based on certain criteria (such as when a specific log message is seen or at a certain time/date). You can either define actions in a sequence for it to run, or you can have it execute a script stored on the device, etc.
You can read more about EEM in IOS-XR at https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5xx/system-monitoring/66x/b-system-monitoring-cg-66x-ncs540/cg_65_configuring_and_managing_embedded_event_manager_policies.pdf