I have an English Toy Terrier and they would fit your requirements. I know you didn’t ask about other breeds, but thought I would be cheeky and jump in, as ETTs are on the vulnerable breeds list and had their lowest numbers ever last year, which is absolutely tragic for such a fantastic little dogs. Half the problem is that no-one has ever heard of them, so we really need to raise their profile. I have had dogs for well over 30 years and had never heard of them before I happened across some information while researching breeds that would suit us.
Not quite as small as a Chihuahua, but still a toy breed that fits nicely on your lap and love their cuddles. Lots of them live happily with just short walks, but they are equally capable of enjoying camping, hiking, agility, etc. They also absolutely adore snuggling under blankets close to their people. Some of them aren’t keen on rain or water in general, but mine is perfectly happy to go out in all weathers (they’re single coated though, so he does have a fleece and a coat for colder weather) and loves his paddling pool and going in the sea. To be honest, I think some of that is down to early socialisation though.
Ours comes everywhere with us and after always having big dogs in the past, it’s been a revelation having one that we can easily take in shops, cafes, pubs, on public transport etc. Half the time, no-body even notices he’s there as he’s so well behaved, the other half we are stopped every few steps for people to ask what breed he is… or if he’s a Doberman puppy!
They are a very natural shape, iysim - full length muzzle, well proportioned frame, no exaggeration or in-bred structural issues at all and for us they just seemed a bit more robust than some more tiny breeds (ETTs are around 30 cm in height). They are so fast too, absolutely beautiful to watch (they have Italian Greyhound in their breeding going back a few generations) when running at full speed.
English Toy Terrier (Black and Tan)
English Toy Terrier Club