Blizzard is working to fix Solo Queue for Battle of Azeroth and Legion
Island Expeditions fell victim to most mechanics, which do not attract attention after the release of new content. Few people already remember about the old raids from the earlier expansion - Battle of Azeroth. Some activities need a team to sign up.
Stay ahead of the questions, there are still plenty of solo players looking to earn Expedition-only items. Valuable items can drop there: from mounts to equipment for Transmog.
Blizzard developers are working on fixes
In one of the interviews, the game director Ion Hazzikostas informed that the developers are aware that currently raids from the Legion and Battle of Azeroth expansion are very difficult to do alone. The team is working on solving the problem and making it easier. However, there was no specific date related to it.
Interesting topics also appeared on the World of Warcraft forum:
Are there any plans to implement a Solo Queue for Warfronts, Island Expeditions, and BfA LFR raids?
We plan on introducing Solo Queues for Island Expeditions, but not for Warfronts at this time due to some technical difficulties.
Generally in the end of the dungeon there will be npcs or other ways for you to teleport out of the instance, but if players still find it difficult we will consider adding more. In terms of the difficulty in farming, our principle is: at the end of an expansion, you will be able to solo the content two expansions ago fairly easily. So by the end of Shadowlands, you should be able to kill the legion raid bosses fairly easily-- might not be able to one shot them, but you will be able to. When that time comes the majority of players will be able to go back farming legion content, and even BFA, perhaps with a small group of people.