on Fdroid like cryptomator or boxcryptor?
I don’t know those two, but termux has gpg, which is an alternative.
I don’t think it is a good idea to use asymmetric encryption for personal use.
I understand asymmetric may have disadvantages like speed, but is there something else?
Note the Goog Cloud talks about using it: Asymmetrische Verschlüsselung | Cloud KMS-Dokumentation | Google Cloud