It sounds like he’s demanding attention, so giving him attention (ie walking, etc) would be reinforcing this behavior (anything that doesn’t stop a behavior, reinforces it).
The best solution to this is the place command. I have a malinois that’s similar. He will demand attention and play all day, if he doesn’t have anything to do. The solution is to give him a job, and that’s the place command. He’s obeying while staying in his bed, which helps him focus, and gives me the break.
Robert has many videos on bed/place/stay. My method is pretty simple and works well. Start by luring (Robert covers this well) and when they know to go to the bed, then go and reward them with increasing duration between rewards. Soon, move to remote rewards (recall them for the reward and back to bed/place).
An easy way to practice is when watching TV. Send the dog to their place while the show is on, then break and give affection during commercials, sending them back to bed when the show resumes. You’ll see progress VERY quickly.
The important part is corrections. If they break the stay (and that’s what they broke, they didn’t break a down or go to bed, because they completed those tasks), then slowly return them to their place under pressure (I use dominant dog collars and apply some pressure).
How much pressure? It’s really easy. Start where you’re comfortable. If they break the stay, it’s not enough so increase it until they stop breaking the stay.
Some tips: Never chase the dog. Never say “No” or anything until you have the leash. NEVER be in a hurry back, the walk back to the place should suck for the dog so they don’t want to break the stay. Do not reward when you get them back. A short leash pop and STAY. At first, don’t wait too long to reward but increase the wait time.
Work the place/stay at home, when that’s good, do it outside in your yard, then other places (only where you can correct). This is the key to a stable, enjoyable dog. Just one persons opinion.