Your comment about your child not liking to be on his tummy gives me a clue. Very likely, maintaining his head up and away from the floor or flat surface is still a big effort for him, and what he hates is his FACE on a flat surface. So he is not ready to sit up alone (very normal, you,ll see a big difference at 7 months) or for crawling (even more normal, 8 months is just about the average for that). And yet, even if his naps last 2 hours each, he,s only sleeping 15 hours a day and has 9 hours to fill...I really think he might be overtired, at least for 2/3 of these hours, but he hates to go to sleep in case he misses something exciting.
The important thing is to stimulate his curiosity, help him explore the world, and do it in a way that will not have you walking him around for hours. You may have tried many of these activities, but I,ll suggest them anyway in case they help:
-Sitting with him in your knees, facing you. Take him by the arms near the wrists and swing him low down your legs and up again to sitting position. Sing along (we have a rhyme talking about sawing a log, in Spain, perhaps you have one there or you can invent one). Same position, move your knees up and down, imitating a horse (and sing along something appropriate). Move your hand around, in a rotating way, in front of his eyes and see if he will imitate you (we sing along five little wolves, the she-wolf had five little wolves, all hidden behind the broom.., in spanish). Count the fingers in his hand, saying that this went shopping for eggs, this lit the fire, this fried the egg, this salted it and this naughty thumb ate it. Or anything else you invent along those lines. Pretend your fingers are a very small child climbing his arm, and tickling him under it. Teach him to say good bye or blow kisses, with his hand, and show him your tongue; see if he imitates all or any of this things (sooner or later, if all this does not bore him, he will).
Some of the above things can be done with him tied to his stroller chair or similar, something that supports him. And there you can provide him with things to explore (not to eat, though at mealtimes you can do that as well): one apple, orange or pear...a piece of paper (big, but not printed and not too soft as he will put it in his mouth) to wrinkle and make a ball of it, try different textures, a cloth, a plastic cup, spoon, dish, keyring with keys, his rattles, that teddy bear you are going to buy, a rubber duck is also good (and good for bath time), a rubber or cloth ball (small but not too small, double the size of his mouth), anything that it,s not breakable, too big to handle or too small (he may choke) and never plastic bags or wrappings. He will eventually drop everything, but he will have explored them.
On a big bed, or blanket on the floor, lying face up: Take him by the wrists and pull him up to a sitting position. Take him by the ankles and lift him until his head his clear, a smooth movement that does not put pressure in his neck at any time and then move him up and down a little, and in a rotating motion (this is called the aviator, most babies love it but some hate it). Try smelling his feet and pretending they stink. Don't ask me why, but many babies love it and laugh. Kiss his stomach, blow on it, pretend you are eating him alive. Tickle him slightly. They also love to be thrown up in the air with you standing up, but if he is heavy it is tiring for you and perhaps scary.
In any position, try peekaboo with him, they usually also love that.
I do not know if any of this will help....but I really feel for you, walking around the house with a cranky baby. It will get easier, but the things I suggest are interaction with mom (not alone with a toy), exploring the world and exploring his own capabilities. Do NOT expect him to crawl yet, it is far too early. Do only what he enjoys, but try what he did not enjoy the following week, as they are developing very quickly at this age. And good luck!
