Yes ... lots!
It started with a replacement boiler and a Hive thermostat, which in time has become the least viable use-case for smart tech. I simply don't want my heating turning off when a window opens or when I leave the house. Most importantly (take note) this is from the earlier type of smart tech which requires a permanent internet connection for the controller app to actually work. Many of the older style (and this includes Alexa) does the processing in the manufacturer data centre and sends the instruction back to your house.
With Alexa, there was some work on being able to support the zigbee protocol generally, but it was patchy at best. I have read they have it in the works that processing will be done locally and won't require a live internet connection ... maybe it's a thing now, dunno.
What I found over the few years of using smart tech is that it is a huge jumble of unconnectable and non-interoperable stuff that really ought to be a lot easier, especially given it all sits on an open protocol called zigbee. If you're a nerd, yes, there's HomeAssistant and that will make the lot work together perfectly well.
As an example, you can buy cheap buttons from Aqara but the Aqara app will only work with Aqara stuff, so unless you want to operate a curtain or blind you're pretty much stuffed. Yes, it'll all work swimmingly with Apple HomeKit and that is where you can get the buttons to connect to a whole heap of other stuff which might be supported by Apple HomeKit < not everything is and it tends to be the more expensive stuff. The buttons don't work in Alexa (well, actually something happened in the last month and now they do but nobody else seems to have realised).
Another example is the temperature sensors from, say, Aqara which can do temperature, humidity and air pressure - all these can be seen the Aqara app but only the temperature is visible in Alexa and only the temperature and humidity in HomeKit.
Yet another example is the Hive stuff - so, you can get the contact sensors (for doors and windows) which say they're HomeKit compatible but actually, they don't work at all in HomeKit, just Alexa ... but then you can't use them to trigger anything in Alexa because you need a logic/automation engine like HomeKit has.
Urgh!
So, at the top I said I have a lot of smart tech ...
Yes, I do ... and no doubt you want the shortcut to what it is you should buy. Well, the answer there is always based on what do you want to do?
In the simplest sense, much home automation can be achieved through cheap inbuild RFID/light sensor lights which you can put in cupboards and so on. Voila! Open the door and the light comes on. I have several in cupboards and one above the loo, so I can shamble into the bathroom in the middle of the night without having to put the light on and wake myself up!
Then there's the more complex ...
I have a number of plugs from Meross, bulbs from Meross, THP/TVOC sensors from Aqara, buttons from Aqara and the Hive heating system. All of that is tied together through Apple HomeKit which uses an Apple HomePod as the "at home base" (equivalent of an Alexahub speaker). I use Apple HomeKit app and that ties together all sorts of automations and multiple operations on the buttons.
Simple one is by the bed, I have a button which when pushed once runs the goodnight scene which turns all sorts of tech in the house off (also saving energy) and a couple of night lights on. Press twice (double-click) and all the lights through the whole house come on - kinda like an emergency situation. I have several automations, like certain lights coming on at sunset or off at midnight regardless ... or our night lights (triggered manually at night) going off at sunrise.
With automation and buttons, I don't need to use my mouth "Alexa ... do this ... do that ... whatever" and so can avoid that awful thing. Don't get me started on Google Home - dear lord, that's crap! I do have Alexa available, because I do have Amazon Firestick TV devices, so I can say "Alexa, show me the garden" and the respective Blink camera will show on the TV.
Ah, cameras ... yeah, whole heap of random there. Blink is cheap and cheerful, but without a subscription and a live internet they're pretty useless. I say useless, but for what? For security, they're useless. For having a camera in a place you don't want to run a wire to they're actually okay. No subscription and you can still save video to a USB stick, but it's not as slick as with a subscription. I have a few around the garden, pointed at exterior doors and watching the woodland at the back for the wildlife - badgers, foxes and even deer.
... but in short, it's a bit of a bind to get much of this stuff working together in any single application. HomeKit is about as close as I've got for most of my stuff, but it comes up short for voice (Siri is crap ... Alexa is massively better, but annoying) and as I said, tends to be the more expensive stuff that is compatible. But, you get what you pay for. Alexa might be a good start, but you'll need to find your own path as to what you want to do and whether it'll work together with everything else.
Used from outside of the house? Very rarely, but I have had to connect back and double-check I'd turned the whatever off (like the Christmas tree lights) ... and I run a slightly different routine on the lights and things when we're on holiday. I do have a Blink doorbell, which has been useful on only a couple of occasions but for me and generally more of an interruption (plinging my phone), mostly it's a convenience thing of having a button/switch that can run a scene to do multiple things and being able to have those things automate, predominantly at sunset/sunrise or only on weekdays.
