Hi shrike! I think any place to start is a good one here, so:
What do you want to be able to do? What sort of physical things do you like to do? What sort of physical things do you not mind doing?
I personally had a hard time working out inside my house during early COVID, but stepping just outside let me have a space where I could get into that mindset.
If I was starting from scratch, I'd start moving more and doing physical things that didn't cause me pain. Is it possible for you start doing a 20 minute walk each day?
I currently walk around inside my house on lifting days - it helps with soreness, seems to boost my cardio, and lets me read.
I think weight training is a great way to go, but there's no need to rush into it. What weight are your dumbbells?
If I just had light dumbbells, and didn't feel a need to push for heavy weights yet, I'd probably do a circuit that hits the whole body 2-3 times a week. Something like:
Db rdl - 1 set of 5-30
Db goblet squat - 1 set of 5-30
Db row - 1 set of 5-30
Db floor press - 1 set of 5-30
I'd start with a single set of 5 on each (that should feel very easy) and add 5 or so reps each session. Once 30 reps is easy, I'd start the cycle over with 2 sets of 5 (this is loosely based off the Tactical Barbell SE work, but heavily adapted).
There's been a million words written about starting as a beginner, and I don't think there's a wrong way to go about it as long as you get moving, start slow, progress steadily, and give yourself time to grow and adapt.
It's definitely doable!