A question… is it possible to get every item in the game without mods or cheating? Let’s say you need Work Boots AND a Femur (weapon)? They are both in the level 10 chest (excluding that you can obtain it from fishing) so you could only get one or the other in a single player game, correct?
Also there is a painting you can only find on the Island Farm, so what happens if you choose another farm? Can things like that still be obtained?
Every item in one save file? Impossible.
One or two like the Panda hat, had certain conditions to be met, that most players worldwide couldn't.
With careful selection and planning, you can get the normally available items. But you have to use multiplayer, especially for Femur and your original save, should had been created with "Remixed Mine Rewards" activated. Then, perform the "glitch", with changing World Seed, so as the Femur appears and keep changing it, until all the items you want show up.
A special painting is only available in the Beach Farm.
If you want all portraits and all spouse exclusive items, you have to marry -> earn items -> divorce -> remarry through all 13 of them (Krobus included)... And still, you cannot get Penny's 3 comlete sets, but only 1 of them, since it works only once; then get the rest during the Desert Festival, but those found there are not the full range.
Last but not least, earning the Junimo !@#$ cabinet $#@! would be the hardest task of all, inside the entire game. I cannot see myself succeeding at that, despite having done almost everything else the game has to offer and you can collect.