It’s also, maybe, worth mentioning the Sandbox is setup having its origin at center (0,0,0) and goes -16384,16384,-16384 to 16384,16384,16384. So, yes – you have 32768 units (meters) in all 3 axis.
Keep in mind, if you begin to use space far from origin (0,0,0) – you can run into problems – floating point rounding errors can lead to oddities trying to precisely place small objects at exact positions toward the extremes. That seems more a problem with the edit tools than underlying architecture, but, either way it can be a problem.
Your upstream bandwidth at 30Mb/s will limit maximal visitors. Ignoring asset transfers (if you use ATP) - you’ll need about 2Mb/s per avatar present (not precise – I haven’t actually measured used bandwidth per avatar in a while – it might be a little lighter now). If using ATP asset server each visitor will consume a large portion of your outbound bandwidth downloading your scene on their first visit (or any subsequent visit if objects not cached). This is why I use either a digital ocean droplet or Linode droplet for anything public – my locally hosted domains are strictly for testing and I wouldn’t expect to have more than 2 or 3 avatars concurrently, which is about all my upstream home net connection could handle, if that.
Long story short - if all you care about is maybe having 2 or 3 visitors plus yourself then host it at home. If you want more than that then you’ll need to get servers onto machines with much better bandwidth.