best firewall option on Debian 10 desktop

[vryni]

With Debian 9 i used to install UFW and access the before.rules file
to make some minor settings changes which gave me a sense of being firewalled.

Having recently installed Debian 10, I've just learned that apparmor is preinstalled
and running by deault.
Beyond that, i am clueless

Should i spend time to learn apparmor settings ?
What is my best option to having my desktop reasonably firewalled ASAP ?

[andre@home]

apparmor seems to to work on application level, similar to Zonealarm on Windows.
iptables or nftables : close normally all ports (=with the starting rule) and then you add which port(s) must be open. Although most programs have there own port (designed per protocol like ftp on port 21).
So incomparable, you wil;l have to decide.
On Linux I prefer the route for iptables or nftables . All ports are closed, unless..... but its only my preference.

[Head_on_a_Stick]

Apparmor is not a firewall.

close normally all ports

All ports are closed by default and are not opened unless a process is listening on them.

@OP: why do you think you need a firewall?

[andre@home]

Indeed as Zonealarm is also not a firewall,.... should have added 1 word.

On Linux I prefer the route for iptables or nftables . All ports are closed, unless.....

I already mentioned it, 1 sentence further