You should first check if somebody else came up with the same idea. The first place is usually a patent database. Even if you are a complete novice, you can glean valuable information by searching for patents which have keywords related to the crux of your invention. Most inventions are enhancements of existing ones, so don't be discouraged if you find patents describing similar inventions. As long as you have an aspect which is novel, it might be patentable.
However, what other people said about patents holds true: most are worthless even after you get them issued, and statistically individual inventor patents are even more likely to be worthless. Getting a patent issued with a professional help can cost over $20k. Doing it yourself might be possible, but be prepared to spend months educating yourself in the intricacies of the patent law.
The situation is further complicated by recent changes in patent law which devalued patents significantly and had especially detrimental effect on high-tech patents applicable to FAANG. Just do a search on AIA, IPR, Alice... These changes were pushed through by these same companies because they started their businesses on the shoulders of other companies which had patents. So instead of paying for using other people's technology, they sent lobbyists to Washington and got laws changed. All this couched under the slogan "patent trolls are killing startups!"
You might try getting them to sign an NDA before you show them your idea, but they usually ignore individuals and refuse to sign NDAs with them, AFAIK.
There might be a way for you to talk to them without an NDA and still have a measure of protection. If, after doing the patents search, you are still convinced you have a good idea, and your idea is not "abstract" (ask Alice what that means and good luck finding an answer), you may file a "provisional" patent application. You basically describe your idea in as much detail as you can and file a patent application in a "provisional" form. This means that Patent Office will not start examining it for more than a year. Filing a provisional application is rather cheap (basic fee $75) and you don't need to craft claims, which can be tricky and expensive. After you file the provisional application, you have at least a year before you need to start the hard work on prosecuting your patent. Within this year, you can try talking to FAANG and you can rightfully say you have filed a patent application for your invention. This allows you to share with them the same information already filed in your provisional application.
If you find no traction within this year, you can give up without loosing much. You will have gained some knowledge and experience though.
I am not a lawyer and this advice is not legal advice and is worth as much as you paid for it, eh.