Firstly, I would say there's a couple of good options. The key thing is that you're not looking to optimise and get jacked and so on, so most internet tips are going to be suboptimal for your specific goals.

The first thing I would say is that - and I've forgotten what it's called but it's out there - you can do 5 sets of an exercise split across 12 hours and still make significant progress. Sure, it'll be slower, and no, Mr Olympia doesn't train like it, but it's totally viable.

The evidence out there does exist, but here's my anecdote: I was a very lazy kid, but I had a pullup bar in my room. Throughout the day, when I walked past it, I'd sometimes jump on it and hit a few pull-ups. Eventually I could do about 13 good pull-ups in a row, and I'd do that maybe 2 times a day. It felt good to do, and was no commitment at all, so I just did it. I never thought much of it, until everyone else started hitting the gym, and in getting all macho someone would offer up an arm wrestle... I'd accept the offer and completely melt them. It became a bit of a circus trick, where I'd have one gymlad on each arm and pull them into each other, while everyone frustratedly said 'how??!!!'. Seriously, it works.

The other thing is that Push Pull Leg splits are probably a waste of time. If you're not trying to isolate each one and push them to muscular failure each time, it's just not necessary. In fact, you could even do 'super sets' (doing two different exercises one after another, then resting) of rows/pushups, or whatever oppositional movement. It would be completely fine, especially if you did that 3 times split across a whole day.

The other key is that without proper equipment, you'll become too strong for a lot of exercises on the ground or off the side of a chair to do them in the 6-12 rep range (which is said to best for building size/strength), BUT, that doesn't necessarily matter. You're not looking for size, you're looking for health. Right now, I'm strong as a bastard but unfit as a sloth. If I were actually healthy, I'd have a more balanced routine involving more endurance sized sets (12 to however many reps you want) or smaller breaks and supersets, to really burn the calories and get my heart rate up. But alas, I am chasing size by lifting heavy and taking long breaks.

For pushups, different progressions and elevation off a chair will keep you busy for a long time. Your dip bar will too. But if you could get the apparatus to have rings - now that's where you hit the sweet spot. I can't stand bar dips now that I've felt the freedom of movement on ring dips and ring rows. Sweet sweet range of movement.

Otherwise - walking. Chasing your kids around. Chasing your dog around (if you have one). Kick a ball with your kids but play as if you were a kid again leaving nothing in reserve. I used to play 'donkey feet' as a kid - where you kick or punch a foot (soccer) ball around high in the air, and whoever it bounces ONCE nearest to has to then hit it up in the air again. If you let it bounce twice, you get a letter added to your D - O - N - K - E - Y. Well, I played it with some friends again the other day. Holy shit, the day after I could barely even walk (in a good way, like every muscle had been stretched), yet in the moment it felt like nothing at all.

Feel free to ask questions or DM, I have spent about 7 years researching and perfecting the laziest and most efficient workout styles possible.