The V2 hub is a matter controller, but not a thread border router. So with just the V2 hub, you can use matter over Wi-Fi devices. If you also want to add matter over thread devices, you would also have to add a thread border router, but there are many of those these days, including some of the Amazon echo models, the HomePod mini, and some of the Google home devices. So you may already have one. 
FAQ: What do I need to add a Matter device to the SmartThings app? Do I need a bridge router device?
Is v2 dead?
It’s not being manufactured anymore, but it’s still a very popular hub, and in fact has more memory than the newer hubs. Most people who currently have them are keeping them.
signal is too weak to make it out of the concrete room the hub lives in
Yeah, concrete buildings are always a challenge. But the advantage of both Zigbee and thread is that they are “mesh networks“ which means pretty much any mains powered device can pass along messages from other main powered devices of the same protocol. So you pass the messages along rather than making the hub do all the work.
In the case of Zigbee, The profile that SmartThings uses can handle up to 15 hops into the hub and then another 15 out again, so that’s usually enough to get a message from one side of the house to the other although you may have to be careful about placement of the repeating devices. There are some people in concrete or Adobe houses who end up putting a hub on each floor just because it’s too hard to get signal from one floor to another, but that’s just something you have to try and see.
Start with post 11 in the following thread (I will link directly to that post), read that, then go up to the top of the thread and read down, and you should learn a lot about how to set up a strong network.
A Guide to Wireless Range & Repeaters - #11 by JDRoberts
But as long as you have wooden doors or fabric curtains on the interior doorways, you’ll probably be able to make it work. If you have metal doors, it could be a problem.
aqara
I personally use both an aqara hub and a SmartThings hub right now. My aqara hub is one of the models that can act as a “matter bridge,” so it can bring many of its devices over to my SmartThings account. That way I get the best of both worlds: I get additional features and excellent reliability in the Aqara app, but I can easily use my aqara sensors in particular in my SmartThings routines. And the connection is local. So that’s another option that only recently became available.
new country
If you use any Z wave devices, then, of course, there is the issue of whether you stayed in the same zwave region, but it didn’t sound like that had become an issue for you.
