Yes. I think it would be hard to find anyone who thinks chagossians should not be consulted in determining what happens with their island.
The stark reality is that it’s probably just not possible, in any meaningful way.
I have first hand experience in this type of negotiation with community / minority group trying to navigate the best outcomes for them with their limited resources, although of course nothing so dramatic as deciding what to do with an island.
The first problem you encounter is that their is very limited governance within the group, or no governance, or extraordinarily poor governance which is acting against the best interests of the group. Straight off the bat you can end up mediating internal disputes which might be generational feuds. For chagossians, you might ask who gets consulted and are they reasonable representatives of the group.
The next problem you encounter is that the demands of the group may very likely be unreasonable and unachievable, and the group might become hostile if they are unmet. For example you might think possible outcomes in this circumstances are stay with UK, join Mauritius, or become a sovereign nation. What happens if the group demands a fourth option, a new island, in the mid latitudes, unpopulated, potential for local fishing industry, et cetera. You can’t really negotiate with a group that would make such a demand.
Another problem is that, well, the stark reality is that maybe the Chagossians don’t really have any meaningful options. What’s the point of negotiating if the only potential outcome is being subsumed by Mauritius and accepting whatever they will provide.
In addition, no matter how much you consult with them, there will always be someone that says they weren’t consulted and they’re bitter because they didn’t receive their new tropical island.
Finally, if things need to be resolved in a timely manner, then involving the Chagossians isn’t going to achieve that. The only option is to hand them over to Mauritius and let them manage all of these issues that have been simmering away since the dawn of time.