You are trying to deploy cloud extensibility proxy through Aria automation Assembler Integration, however post successful deployment it's not getting detected in the portal to configure it further.
/etc/bootstrap/firstboot.log
you see an error -
Job for etcd.service failed because the control process exited with error code. See 'systemctl status etcd.service' and 'journalctl -xe' for details.
VMware Aria Automation Cloud
The most likely cause for this issue is using a short hostname instead of a fully qualified domain name (FQDN) during the CExP deployment.
Verify Hostname: Check the deployed CExP configuration to confirm it uses a short name instead of a FQDN
Redeploy with FQDN: Redeploy the CExP using the correct FQDN. Refer to the Aria Automation documentation for specific deployment instructions: https://docs.vmware.com/en/VMware-Aria-Automation/SaaS/Using-Automation-Assembler/GUID-3F363A84-4F4F-4B77-B38F-547C85F84B7C.html
Using a FQDN ensures proper DNS resolution, which is crucial for the CExP to function correctly.