Nextcloud is excellent, and its Android app is great. I found the Auto-Upload feature to be nigh unusable.
I have 20GiB+ of photos on my phone, so and don't need local access to that on all my PCs, so I created a seperate account just for phone photo uploads, to serve as a backup and allow me to access the photos from the web interface.
Attempting to use Auto-Upload on my camera's folders was messy. It kept uploading photos to the wrong Nextcloud account and kept how many files there were, as well as not supporting bidirectional sync. It was also unpredictable how long it would take to actually trigger an upload, without a manual way of starting one. It also limited automatic uploads to a single folder.
I found using FolderSync a much better experience. It let me simply set up bidirectional sync between custom Nextcloud folders and local folders, let me choose cadence for syncing and allowed me to manually trigger a sync.