Remote access Samba share

I have setup samba share on OpenWrt 23.05. I can access it locally, now I want to access it over the internet.
How can I do it? Should I setup Wireguard? if yes how?

Yes. Wireguard is a great option.

https://openwrt.org/docs/guide-user/services/vpn/wireguard/road-warrior

how can I confirm if I am not behind a CGNAT. I have VDSL connection.

What are the first two octets (in bold: aaa.bbb.ccc.ddd) of the address you see when you issue this command:

ifstatus wan | grep address

root@OpenWrt:~# ifstatus wan | grep address
root@OpenWrt:~# ifstatus wan | grep address
root@OpenWrt:~#

Is this your main router? Do you have a different name for the network interface that is used for the internet connection?

this device is connected via 2.4Ghz wifi to my ISP router

Ah. Ok.

On your isp router, look for the wan address and post the first two octets.

39.46.. this is the public wan ip in isp router

Then you should be good. That is a proper public ip.