Four years ago, at the age of 74, I started playing the piano in order to play the English hymn tunes I miss so much. My learning curve was not improved by eye problems and a back operation. That behind me, I play almost every day and I still love it. I would definitely not recommend my method of learning to everyone but it worked for me.
"Pros" were that I had a very clear idea of what I wanted to achieve and two years violin, basic guitar and touch typing skills, although decades ago, meant that my fingers got the basic idea fairly quickly. Computer skills were a big plus and there was the organist friend who, although he probably thought I was insane, when he saw I was serious, was supportive. His gift of a hymn book with simplified settings was worth its weight in gold.
I moved abroad as a young adult. The only way to learn the local language at that time was to listen and imitate. Doing this, one recognises even the tiniest step forward as real progress. The conviction that ones 'skills' are improving even if it doesn't feel like it, is vital to my motivation.
"Cons" were my age and all the minor disadvantages it brings. I had cataracts in both eyes, glaucoma and double vision, particularly in the evening. Living in a block of flats an acoustic piano was not an option. I had never played the piano before.
Steps to making it a feasible plan were a digital piano and headphones, a pair of glasses with the correct focal length and good lighting. I bought a tutor suitable for use without a teacher, but I also waded straight into SATB hymns. A computer programme for scanning them to enable me to change keys and to remove verses between the two staves helped a lot. I also download Very Easy Piano Scores of classical pieces of music I like. Of course it was all very, very, very slow but this was, and is, irrelevant.
One of the oddest problems I encountered was that when my two eye operations finally enabled me to read the fingerings on the ' Easy Piano' scores, I had a hard job teaching my forefingers that they are no longer "1" as on the violin and the guitar, but are now "2"!
Having a teacher might have meant playing one piece until I could play it well but as I wanted to be able to sight read hymns, not play them to an audience, I moved onto the next tune as soon as the previous one began to be automatic. Recording my playing terrifies me, so if I need a tune for Sunday School, I record the right hand, play it back while adding the left hand, then after speeding it up a little and changing the format, I put it onto a USB stick to take with me. The purists will throw up their hands in horror I guess, but these 'achievements' are very motivating. A piano teacher who, at my request, watched me play recently gave me a couple of tips. Perhaps next year I'll take another lesson for my eightieth birthday.