Anything that is true about those specific devices was true under the old architecture, except that now matter may offer some additional integration options that we didn’t used to have.
As far as Moes, they are a re-brand of Tuya, and the issue with Tuya is that it uses a lot of proprietary code only intended to work with its own hubs. And that’s always been true.
They won’t work with the official integration (and if you get one of their hubs, and the device is not using matter, then you’ll only get the integration you can get through the Smart life app, and that’s pretty limited).
But there are some community developers who have written some edge drivers that do work with some tuya devices.
Find the “fingerprint” of your device (the combination of the manufacturer code, and the model number that you can get at the official web interface to your smartthings account)
Then post that information in the community request thread for Zigbee devices and hopefully someone will know of a custom edge driver that will work with your specific device. (Make sure you read the first post in that thread carefully so you know what information the developers will need to help you).
Post Requests for Zigbee Edge Drivers Here (community-created)
As far as the aqara button, I know that early on there was at least one community driver for it, I’m not sure if it has since been included in the official drivers or not. I do know that it’s supposed to be an absolute pain to pair, with most people saying they had to try four or five times, and some more than a dozen just to get it to connect. 
You can go ahead and post a request for that one in the request thread as well if there isn’t already one posted there.
As far as home assistant: people who are programmers tend to love it, and ask themselves why they didn’t go to that years ago. People who are not programmers often come back to an easier platform after trying it. It’s up to you if you think it’s worth the time to try it. You can look at the category in this forum called “other hubs“ and find some recent discussions, if you’d like to ask people with experience with it. There are also a fair number of community members running both home assistant and smartthings, because they like the smartthings app way more than anything available with home assistant. Choice is good. 