So sorry! Erg is a rowing machine, a popular one being the Concept 2. Actually short for “ergometer” because they measure the work you do.
Yes balance stuff anywhere anytime. That’s why @puzzlegal ’s approach is such a good example. Integrated into daily routines, brief frequent, and able to be progressive. From leaning for support to no support to in dark or putting socks on standing on one foot to heck closed eyes! Sure while watching tv, maybe raising arms up and down.
The best exercises are the ones you do. Getting to the gym is half the battle and the above machine routine will help maintain muscle. But after doing it for well over a year, you’ve probably made gains as fast as you are going to. If not, you’ve probably could be more aggressive about increasing the weight or number of reps. Also, it would probably be worth adding bicep and triceps machines to get more arm work, if you have listed the exercises correctly.
I could suggest another routine. This may not be better, see first sentence. I have kept the number of exercises moderate so things can be completed fairly quickly.
One possible change might be to introduce more dumbbell and barbell stuff to work more muscles. There are many possibilities, one is:
Day 1: bench press, dips, lat machine, tricep machine, abdominal exercise
Day 2: squats, leg extension, bicep curls, assisted chin-ups, abdominal exercise
Day 3: deadlift, rowing variation, leg curl, back extension, abdominal exercise
But if this would reduce motivation the game might not be worth the candle.