Honestly, I find it difficult to answer your question because I can't say exactly how much memory is available to the user. But if you have already found out the answer to this question, I would be glad to read it.
There are a lot of different factors affecting the amount of memory available to the user. Let's start with the fact that each user has their own PC configuration. A lot depends on the characteristics of the computer, the speed of writing, the speed of reading files, the speed of the CPU and GPU. To accurately calculate the amount of available memory, you need to initially know the model and specifications of the video card, processor, RAM memory and most likely the motherboard. I am also sure that in the software itself, you can choose the number of system resources that the program can use. At least in the applications that I made using the service like https://flipabit.dev/, I had the possibility of such a setup.