keepassxc has 2fa support

Seconding KeePassXC. Has good browser integration too.

OTP is built in to many password management applications. I use pass and the pass-otp extension.

You can also use OATH Toolkit’s oathtool(1).

Ente Auth

Bitwarden

If you use Gnome and Flatpaks there is an app called Authenticator on Flathub

Some great recommendations in here already. If you're looking for an OTP only UI: https://gitlab.gnome.org/World/Authenticator

If you use KDE Plasma and want an app which looks like your other Qt apps: https://apps.kde.org/keysmith/

Another idea if you are willing to spend some money is to get a yubikey. Then the tokens are stored on a separate hardware key and it has great android and Linux apps to access codes

I've been using Authenticator and haven't really had any issues.

I imported my Aegis codes and they worked no problem

A chrome extension should do the trick

What exactly do you want it to do? You can implement TOTP with a 10 line python script and I probably have a few of those kicking around. I've ended up doing that at least a couple of times.