Then if Meghan wants to do those endorsements she will. When Andrew and Sarah got divorced, Sarah wrote books and shilled products like Weight Watchers and did so as Sarah, Duchess of York or Sarah Ferguson, Duchesss of York. What stands out to me about Sarah is that in the interviews that she did, when asked questions about the BRF, she was positive and gracious, although she was critical of courtiers. I think that the reason she is considered as having failed is that she was poor at money management and blew threw the money she made, so in my books, she is both a role model and a cautionary tale.
You certainly are not alone in disapproving of royals, whether they are blood royals or married in, engaging in commercial ventures including product endorsements. It is your right to feel that way, but I think that in the case of the Sussexes they need to develop a thick skin against those who disapprove. As we have seen recently, there are other ways for a non-working royal to make money that involve slagging off the BRF, product endorsements are preferable IMO. Also, I think that it is important that they earn their own money and not rely on the kindness of strangers / acquaintances. I think that there are plenty of good people who have been generous to royals in terms of things like letting them use their private planes, vacation homes, etc., and want nothing more that to be seen hobnobbing with a royal, and perhaps an invitation to stay at one of the castles, however I think that you also take the chance that one of these benefactors are a Jeffrey Epstein type.
I think that it is incumbent on the monarch, adult heirs and working royals to do their part to keep the BRF relevant and seen as adding value. The institution of the monarchy should be able to withstand former and tangential members engaging in bad or tacky behavior, sure they may take some hits in the short-term, but as long as the people of a given country are OK with having a monarchy, the institution should not be undermined by the actions of non-active royals.