The new Twitter progressive web app (PWA) which was released almost a month ago to Insiders on Windows 10 Redstone 4 (April 2018 update) or the Skip Ahead Redstone 5 builds, has been updated to add support for pinning profiles to the Start menu, which turns them into Live Tiles.
Through the app, all you need to do is click on a Twitter profile, then the 'Settings' gear and choose 'Pin user'. Upon doing so, you'll be presented with a notification to confirm the choice, as shown below.
Once pinned to the Start menu, the Live Tile will update automatically to display information and media associated with the related account. Unfortunately, that's about all it does at the moment, since there's no option to tweet to the account or send a direct message to the pinned profile. This feature simply allows you to go directly to the profile in the Twitter PWA.
The main application's Live Tile does add several shortcut options such as New Tweet, Explore, Notifications, and Direct Messages, which are available from the tile itself. We spotlighted the app last month - you can read about it here - and essentially, the Twitter PWA is more of a web wrapper compared to the older Twitter UWP app, which is still the only choice for most Windows 10 users who aren't Windows Insiders.