If there is a US, UK or European stock you can’t find in the app, there may be a number of reasons for this:

We simply haven’t added it yet! You can make stock requests here

We may not add highly illiquid stocks if it means there’s a high chance orders won’t go through

Newly IPO’d stocks will be added once they hit the secondary market, which is typically on the day of the IPO or the very next day. More info here