oracle19c - Port 1521 open on remote VM and visible in netstat, but cannot ping with telnet

Question

I am running into some issues while trying to access a remove oracle db 19.3. The VM (CentOS 7) is located inside GCP Cloud and I can ping it on other ports (22), but i cannot connect to the database using sqldeveloper or even ping port 1521 with telnet.

The firewall is disabled and the lsnrctl status is up, but i'm a bit worried about the output:

LSNRCTL for Linux: Version 19.0.0.0.0 - Production on 30-MAR-2023 18:13:07 Copyright (c) 1991, 2019, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=)(PORT=1521))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 19.0.0.0.0 - Production Start Date 30-MAR-2023 16:54:43 Uptime 0 days 1 hr. 18 min. 24 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /oracle/product/19.3/db_home/network/admin/listener.ora Listener Log File /oracle/diag/tnslsnr/oracle-19c/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oracle-19c.c.enhanced-tuner-382015.internal)(PORT=1521))) Services Summary... Service "CDB" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... Service "CDBXDB" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... Service "f810a6809fc55a12e0530300840a2cc0" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... Service "f810a75fde6b5b22e0530300840a8ce6" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... Service "orcl" has 1 instance(s). Instance "orcl", status UNKNOWN, has 1 handler(s) for this service... Service "pdb1" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... Service "pdb2" has 1 instance(s). Instance "CDB", status READY, has 1 handler(s) for this service... The command completed successfully 

Here is the output for the netstat -tlpn | grep 1521:

tcp6 0 0 :::1521 :::* LISTEN 1298/tnslsnr 

Also, the 3 files *.ora files were not added from the start inside $ORACLE_HOME/network/admin/, so i've added them from the 'samples/', but I think most of them are empty/commented out.

I've also tried reenabling firewalld service and starting it, adding a firewall exception for the port, and also adding a firewall exception in GCP, but still cannot make it happen.

Please let me know what else I am missing. Thanks!