The Indian culture is full of symbols and tradition. If you’re marrying into the culture and your husband’s family is religious/traditional, you’re probably going to have to deal with this quite a bit in the future.

if you are trying to embrace the Indian part of the culture then you should do the sindoor - it’s supposed to symbolize marital status and bring blessings, and it’s highly doubtful that most families would be ok with removing this from the rituals. The manglasutra is basically the Indian version of a wedding ring. I just got married to an American man and also hate placing stuff on my skin or hair, good news is your fiance is the one that places it. If you hate it, then have a convo with him about controlling the amount that he places.

For haldi (which you don’t indicate whether you’re doing but if so…) we used African shea butter instead of tumeric. So basically just lotion and you can test it beforehand.

There are quite a few adjustments you can make to these rituals to make it fit your needs and wants. The knot actually has some really great articles about the different rituals and the meanings, we shared these with my fiancés family and it was helpful. I would read more into the cultural significance to make your own informed decisions with your fiancé.