We finally got a dog 2 years ago, after waiting for several years to be in the right position to be able to care for a dog without huge problems.
She has been a mental health life savers for me and DD, so happy, loving and carefree - welcomes us if we are out even just popping out for a pint of milk. So happy when the alarm goes off and there's a new day, and just is so excited to wake up and be with us. We got her in September 2020, so our lives have changed massively, I now WFH 95% of the time.
DM is in walking distance and is dog care backup, and has thought about getting a dog but couldn't commit to the dog's needs. So she is very happy to have DDog and be a substitute dog owner. That was part of being able to get a dog, as when we got her the assumption was I'd be in the office 5 days per week. If DDog would be with her any length of time (more than a couple of days) I would get a dog walker to come and give her a good long walk to add to DM's walks round the block and play in the garden.
I have made a number of local friends through walking DDog at the same time each day in the park, and now have (never something I expected) several other people happy to have DDog if we're out, just as I have had their dogs when they needed occasional dog care.
In the last week we have gone down with the horrible germs going around, and DDog had 3 days without a proper walk. She's been bored but not destructive - tried to get us to play, but sighing and accepting it when not getting a response.
She was a stray, about 7 months old when we got her from an overseas rescue with a UK partner that brought dogs over and fostered them until placed.
The drawbacks - limited overseas holidays, it wouldn't be fair to DM. At this point this is minor, as DM is fit and healthy. As long as DM is able to get up to let DDog out in the garden this won't be a problem, as I would organise a dog walker for the longer walk, and DM loves having DDog around. But DDog is only 3, and DM is in her 80s. OTOH as DDog gets older she will need less activity and be just as happy to snooze on the sofa with someone familiar.