There are lots of people who just lift, and they're very fit. But they lift really heavy, and do the classic compound lifts with a barbell generally - so you can lift a lot heavier than Caroline Girvan's routines. Squat, deadlift, and benchpress - where you're not limited by your grip, so you get to lifting weights near to, or even equivalent to your body weight.
The 10,000 steps per day is good - maybe aim for 15,000? (that's my target)
But recently "hybrid" has become fashionable, particularly training for things like a Hyrox race, or the Deadly Dozen.
My training sessions tend to be strength (I lift heavy) then metcon (like HIIT, I suppose, but a lot more functional stuff eg plyo box jumps) - 30 minutes each, 3-4 times a week. But it took a long time to get so fit that I can manage that. And it's not all running: SkiErg, assault bike, rower, dumbbell thrusters, burpees - a lot of moving around.
If you wanted to get running again, I'd do it on the days you aren't lifting. And I'd be looking at just how heavy I could lift - just doing mostly accessory lifts with dumbbells won't get you the heart fitness you're looking for, I don't think - but 4 sets of 4 reps of barbell squats at near to bodyweight will. My deadlifts last week were did 3 sets of 2 reps at 100 kilos with 2 mins recovery between sets. I was out of breath & quite tired after just those 6 reps! That's the training effect.
With just 15k & 10k dumbbells (as in Girvan's Iron day 9) it's going to be pretty aerobic, though.