Do you mean reflash NikGapps-full-arm64-12.1-20220908-signed.zip or what addon do you refere to? I did not find a AA specific addon in nikgapps repo.
No. You need the same version addon. If you install nikgapps S, you need android auto s addon https://sourceforge.net/projects/nikgapps/files/Releases/Addons-S/08-Sep-2022/ NikGapps-Addon-12-AndroidAuto-20220908-firmado.zip
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