have you checked rclone? you can use it on android using termux app. you can sync your local files to cloud storage like google drive. you can also encrypt the files. the only downside is that you have to manually run the command to sync your files to the cloud storage but you can create a script. there is also an open source app (round sync) that uses rclone but many features are missing, only sync and copy are available but there is an option that you can schedule the syncing of files to cloud storage.

logseq is awesome but their mobile version is still very unstable and has no plugins, only custom css.

i use fennec f-droid, it is based on the latest firefox release with proprietary and telemetry removed. tried mull before but site often breaks and slow when searching so i switched to fennec.

• keepassdx - password management
• aegis - offline 2-fa
• obtainium - download apk from github, gitlab, f-droid, and many more sources
• k-9 mail - best email client