This year I had like so much fruit that many went to compost. The largest fruit reached 600g and smallest 200 g. one tree produced 5 kg per year.
I overwinter them at 12 C. They don't need water in a humid greenhouse.
If you pot them in ground then transfer them into pot they will die, they don't like to be moved. The root system is very sensitive. Just leave them in a big pot, the bigger the better. Plant them in spring and in winter you will have many fruits. I used to have 12 trees, but because people find the fruit strange, it's not very popular. Very low sugar content, lots of juice with an intense aroma of lemon mixed with pineapple. The juice can slightly burn your lips.
Your plant in the picture suffered form root rot, unfortunately you can't do anything to save it, maybe take a cutting to propagate, but with slim chances.