I can't find any more info on the Saudi law, but I believe the EU law at least has provisions for moving to a new standard in the future if a better alternative comes along. So when USB-D arrives, if it is seen to be a better standard, the EU can mandate that it becomes the new charging standard.
So far, nothing I’ve ever owned has had a C connector, I have two computers with c ports, but nothing to plug in to them. Also, does the thunderbolt look like the USBc? If you plug in a thunderbolt device into a USBc, does it work or burn out the port?
Just about everything except truly basement-tier China tech sitting in warehouses has C now so you'll soon be glad to have the ports.
USB C is a form factor (pretty little reversible oval cable). Thunderbolt is a protocol and yes it uses USB C for the form factor. Other protocols on USB C cabling include 2.0 (ancient speed, used for charging only these days), 3.1 (old speed) 3.2 (slightly old but also not, it's weird, and most common nowadays), DisplayPort (lovely modern video standard), and USB4 (which is newest and fast, but not quite as fast as TB). Decent rule of thumb is USB4 will always be one step behind Thunderbolt in speed (currently ~80gbps vs 40gbps in USB4). The cable will work at the fastest speed permitted by both devices. If they both have TB, then TB speed and power. If only one is TB, it'll go at USB speed over yes the same cable because...
Lastly, any proper spec cable will negotiate the best, safest power transfer between chargers and devices. So just don't buy complete junk, read a couple reviews, you'll almost certainly be fine.
These laws are fine until something better than c comes out. Then we have to wait for laws to be updated to make changes. We all know how slow government moves.
That kind of things are not wrote as laws. What they usually do, is wrote a law creating a regulatory body, or given the power to an existing one, that can determine how it works. So, when new technologies come around, the regulator just need to update the regulations without the need of a new law.
USB-C isn't better than lighting when it comes to being a port on your phone. With how poorly implemented C is on most devices, the only thing it would have going for it is the interior ability of USB 2.0.