I tried doing this as a side thing but it doesn’t bring in much money.
Communication with people about sizing can also be problematic, there is a manufacturers size chart available for the bulk bags of blank press on’s but people are still very wary of measurements and don’t generally want to pay the small cost of purchasing a size sample pack.
I found that Press on nails sell for a lot less than an average manicure, with a lot of work and product going into them depending on what you are using.
Using gel really is messy, and also not cost effective due to the average sales prices. It’s not something to use your expensive gels and glitters etc for.
There are also issues surrounding glue and the natural nail, also with nail glue getting lots of media attention recently for some nasty accidents - I did not sell or include nail glue for those reasons.
I don’t think it’s worth it at all, it’s a slow game unless you are selling them at really low prices - which after using your lovely products on and then fees for all the services involved is just not worth it.