This is your interpretation of Quran 2:184
“Just for a fixed number of days. But if any of you is sick or is on a journey, he may make up the same number of days later. For those who can go through 'Saum' only with hardship, there is an alternative: the feeding of an indigent. But the one who gives more on his own volition, it will be good for him. However, going through the training program of 'Saum' is good for you if you knew better.”
Who are those who go through ‘saum’ only with hardship? Are they the sick and those on journey? If yes, does it mean alternatively they can feed an indigent for each days missed due to travel or illness?