Chronic Issue: Improve Matrix.to

### This is a chronic issue

**Problem:**
Users should be able to follow [matrix.to](http://matrix.to/) links on mobile, even if they haven't got Element installed yet, and deeplink into the correct room/space/user - rather than end up on the default homeserver in the default place, and then get lost trying to get to their final destination.

**Defect:**
Following a matrix.to link does not onboard you to the room in question. **On mobile we need the clipboard hack to take you to the right room \(& hs\)**
- \[ \] https://github.com/vector-im/element-android/issues/7673
- \[ \] https://github.com/vector-im/element-ios/issues/7129

**Suggested solution:**
It's awful that onboarding via links to public rooms simply doesn't work if you're on mobile \(unless you have the app installed\). Google-photo style onboarding. See also [https://github.com/matrix-org/matrix.to/issues/263](https://www.google.com/url?q=https://github.com/matrix-org/matrix.to/issues/263&sa=D&source=editors&ust=1660233670690135&usg=AOvVaw36i7lE-1Za92Ju6ruM-73C)

## Plan

The Delight team will take this chronic issue as a part of the [Account Resurrection cycle](https://github.com/vector-im/element-meta/issues/619).

More information on what could fall in or out of scope for this cycle can be found [in the Delight team roadmap](https://docs.google.com/spreadsheets/d/1SAcCgnHoze9Flqx-XXkC0B8iQyLnpylv2z4iidK0v-8/edit#gid=42666095&range=C23) or on the [Delight team board](https://github.com/orgs/vector-im/projects/20/)

Start with the linked Element Android issue 7673 and Element iOS issue 7129, then review the Account Resurrection cycle and its Delight team roadmap. Done means a mobile matrix.to link on a device without Element installed can onboard the user and deep-link to the correct room, space, user, and homeserver.

Written by the indexing model from the issue text.