There is definitely a way back for the Duke and Duchess.
I don't mean a way to build back their 'brand' and make money but to rebuild their relationships and regain other's respect and their own self respect.
The Nigerian tour is nonsense. It's supposed to make people ignore the fact that they burned all these bridges in Britain where they were real royalty and part of an organized system where they could do good. The system is not perfect and requires a lot of hard work in return for a little (surprisingly little) glamour. Diana worked within this system, even after being divorced and put in sweat for years and it's because of that that she managed to make changes in the way they did things that needed to be changed.
Meghan and Harry threw out the baby with the bathwater and said things that remain out there that threaten the system greatly. This is totally outside of the personal relationships in the family, where as I said before, all probably bear some fault. This is just what they did to 'the Firm.'
Now Harry is out there with this one thing, Invictus, which mostly at this point shows what he's capable of and no longer has an opportunity to do, and Meghan is flitting around unmoored from all advice and giving a sound bite here and a sound bite there, in the midst of a lot of failing self promotion and we get things like this tour.
Nigeria is in horrible shape
https://www.npr.org/2024/04/09/1241997352/nigeria-kidnap-mass-abduction-chibok-girls
1,000 people kidnapped in the last few months. Sickening murders by the Fulani tribesmen. Look it up. Though much of it is not in the news. The Duke and Duchess's 'tour' promotes selves, glosses all this over and gives a failing regime positive publicity and does no long term good. They are capable of more for sure. There may not be a way back into the royal family as a 'Firm' (though hopefully there is eventually into the family as a family) but if they really truly want to do good outside of the family, as in 'service is for everyone ' they need to take a long hard long at what they have done wrong up to this point and I think look at what the Royal Family does right, take some advice (there was a good post on this awhile back) and make up their minds to do a lot of slogging, grinding work, comebacks are possible but take a while and aren't easy.
They also should focus on what's possible. Her Majesty the Late Queen was very right. Half in, half out does not work. You can't both run a charitable organization well on your own and be a Hollywood star/influencer at the same time; you have to decide which you really want to do and keep at it.