For the 2016 USB-C model, a missing internal SSD requires a complete Logic Board replacement since the SSD is soldered onto the Logic Board. It will be an expensive repair. I would recommend putting the repair money towards a replacement laptop instead since the 2016 model has so many known design & manufacturing flaws.
Plus the 2016 model is now considered "Vintage" so repairs are only possible if the necessary part(s) are still available. There is also an added risk with repairing a "Vintage" device.....if the replacement part fails within 90 days, Apple may not be able to honor the 90 day part warranty.
By the end of 2024 macOS Monterey will no longer be supported by Apple. When this happens many third party apps may no longer receive updates either. While these third party apps will continue to work for a while, sooner or later any apps which are part of an online service (for example web browsers) may slowly become less able to access the Internet and online services as both the Internet & those online services change. AFAIK, all the popular third party web browsers are now only fully supporting the current version of macOS & the last two versions....at this time they are Sonoma, Ventura, and Monterey respectively.