It seems Opera does support wayland perfectly fine, you can execute it as such:

opera --enable-features=UseOzonePlatform --ozone-platform=wayland %U

Though it seems when editing opera.desktop it doesn't has the desired effect, put this here ~/.local/share/applications/opera.desktop:

[Desktop Entry]
Version=1.0
Name=Opera
GenericName=Web browser
Comment=Fast and secure web browser
TryExec=opera
Exec=opera --enable-features=UseOzonePlatform --ozone-platform=wayland %U
Terminal=false
Icon=opera
Type=Application
Categories=Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml_xml;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;application/x-opera-download;
Actions=new-window;new-private-window;

[Desktop Action new-window]
Name=New Window
Exec=opera --new-window --enable-features=UseOzonePlatform --ozone-platform=wayland
TargetEnvironment=Unity

[Desktop Action new-private-window]
Name=New Private Window
Exec=opera --incognito --enable-features=UseOzonePlatform --ozone-platform=wayland
TargetEnvironment=Unity

Hope that helps!