@stuts Fedibird is a fork of mastodon that has a feature like that called domain subscription. With that you can add any domain that is a mastodon instance to any list, and all toots from that domain will go to that list. You can view the local timeline in a separate column through the context menu on a specific toot. Qoto also incorporates these changes.
All of this is still subject to the usual limitations of activity pub protocol - you will not see users/toots from other instances that nobody from your instance ever interacted with (it is basically just a filter for federated timeline). In order to see the full local timeline you need to request it from the instance directly (it may reject, but most don't). Unfortunately not many clients allow you to make such requests. I only know of 2 that do, subway tooter and fedilab, both android only.
@namark Thanks for the tips! I mainly access the fediverse through web browser on my laptop so was ideally looking for something that supported desktop/web to do such a thing.
I'll have a look into those apps and try to ramp up my mobile usage but certainly prefer the wide, multi-column web view!