Uploading photos from phone to computer always works for me with airdrop. Sometimes balky, but it always goes. That can be diagnosed by an Apple genius. It otta work every time. Further, you get xyz amount of free space on iCloud, so it transfers photos and keeps them. Any device can pick it up by accessing iCloud storage, even a browser with an iCloud.com login (in preferences, allow access via web).
When dealing with windows and android users, I get or buy for the other person PhotoSync. It transfers from everything to everything (less Linux, probably)
Finally, a cable and ImageTransfer on the computer has to work or your gadgets are broken. Nice for transferring the entire camera roll. I do it as a backup for my phone photos. I can erase them all and get them back any old time.
I have been using imgbb.com and postimages.org.
They drag and drop on a computer, or let you pick from your albums on the phone.
Imgbb.com will give you a URL you have to strip out all but the src= part. Nuisance but the direct link is great.
I use postimages to resize (its more obvious how to do so) say to 480 by 680 or whatever, to even up images. DU takes the direct link readily, Fewest steps. Its not really a direct link, but DU takes care of things. My FAFO flag collection is all via postimages.
https://www.democraticunderground.com/100219770873
They will do multiple uploads (nice). In postimages, ask for direct link and it will give you a list of direct links.
Everyone has their own ways of doing this stuff. I believe in Laziness is the mother of invention so the fewest steps the best for me.
My experience is that everything is faster by far on a computer compared to a mobile device. But the 27 inch monitor doesnt fit on my lap on the easy chair, so there you go.
This was composed on an iPad Pro sitting on top of my piano, where it 99% of the time shows my music scores. The keyboard case makes typing a zillion times faster than the on-screen widget.
Good Luck.