Awesome writeup thank you.
As you might know we live in very different worlds! Here the cheapest data plan you can purchase would be 15000 Naira for 500mg (0.5GB) of data. The cheapest phone you can realistcally purchase would be a Samsung A03S (or maybe A04) which will run about 160,000 Naira (120,000) on sale. Finding plans and phones like the ones you mentioned simply don't exist here. I found what I did simply because I have no access to the items you have there and I am 100% certain that even the most basic itel A18S model would outperform anything that I looked at!
With that being said I'll give a few thoughts ...
You are absolutely right, getting the latest version of Android is usually a very good idea. Going too far back and things just won't work right. I had an old One Plus One phone. It's cameras were great. It was still fairly fast and had good specs. However, it had an old version of android and even some basic sites were beyond it.
With regard to memory and storage space. Of course more is better. However, even that little 2" cellphone I have with 10GB of storage does its job admirally. I just make sure it is laser focused on what I do with it. It doesn't get many apps put on it and only things necessary for communication and posting were added. Having said that I also purchased a Samsung A03S which is lacking in memory and storage space. I used it extensively on my trip to the Philippines. Without games and unessential apps it never had issues whatsoever. I'll say it IS possible to run a more basic phone but it requires more dedication to being mindful of what you put on it.
With regard to battery size. Larger batteries are very nice but 5000mAh only tells half of the story. My Samsung A03S with a 5000mah battery lasts a very very long time (up to 3 days) while my Samsung S20FE or my wife's S23 Ultra (4500mah and 3900mah) are lucky to make it until the end of the day. Indeed My S20FE will often be at 40% after an hour walking the dog playing Cubieverse. The biggest difference is that a basic phone with low power CPU and less bright screen uses a lot less power so needs a much smaller battery.
Hopefully @rare-gem reads this post because there is a good chance she'll be doing a mission next month and has expressed an interest in getting a phone to give away. I'd be really curious how the Itel phone works.
Which brings up the final point. I do understand your hesitance with brands you don't know. I've tried some "no name" brands and have found them to be total garbage. Then again, I've tried some "no name" brands and have procured some truly awesome hidden gems which far exceeded my expectations. Of course when finances are as tight as they seem to be in Nigeria I'd probably follow your viewpoint and get something tested as reliable. It just makes good financial sense to get something more durable.
Again, thanks for the post :) Appreciated.
I'm glad this post interests you and brings us on common ground. You're right about the battery as regards different specs and CPU.
Thank you for your time, it's always a pleasure engaging with you sir