Just wanted to chime in to give some personal experience with Nextcloud.
I am running Nextcloud in a iocage jail and also running originally in FreeNAS, now TrueNAS CORE.
I have an Android phone and I use the Nextcloud App.
I have configured the Nextcloud App to upload automatically to the server the pictures and videos I take with the phone.
I do the same with the Download folder which is used while browsing the net.
I use Whatsapp, but stay away from Google Drive and Google Photo.
I have other Apps that connect to the server for automatic uploads.
When Nextcloud App uploads the phone pictures and video, the content of the Download folder and whatever folder it is asked to monitor, the files will be uploaded to the server without compression and filenames will remain exactly the same.
I also use the option under the Nextcloud App to create subfolder with dates. So things can be very tidy.
What I have noticed is that files shared with Google Photo and Whatsapp will be resized causing loss of details. You have to blame Google for that, especially if you are not using the paid service. I don't know the details for users buying a phone with unlimited Google Photo as part of the deal.
When my phone is sending videos and pictures away from home, it is possible connection quality could cause the transfer to fail, however I can resume the transfer manually and for that I make sure the file is sent from scratch, just to prevent possible file damage.
Some of the larger videos taken by the phone exceed 3GB in size.
If I am traveling and I carry my DSLR, then I must carry with me my laptop so I can transfer the content of the DSLR memory card to the laptop in the folder location the Nextcloud program handle the file. They get uploaded automatically whenever I have access to Wifi or LAN. Same behavior as the phone, the files are transferred as is without being modified in any way.
I have been using Nextcloud (owncloud back then, prior to the fork) for over 8 years now. No complaints whatsoever when it comes to trusting my data.
In regard to above mentioned "original" vs "some other folder name", my understanding is that some phones do a lot of processing in the background and can store the data under multiple files/folders. If we take HDR, the phone will take multiple shots at different light levels and combine them. You may end up with an HDR folder and a JPEG folder.
If the phone is allowed to upload the files to Google Photo, it is possible the App on the phone is resampling the original file and only upload the data Google Photo expect to see to fit its Free Account maximum requirement.