Tbh the best way to avoid that is to use marketing instead of force, make carrying a reusable spork cool, market it differently to people (like for the woke say it's green and one company that makes a certain spork is employee owned by gay people, for the trumpets say it's good for their prepping or because the microplastics are estrogenating the children or some shit and also this other spork brand are god fearin' christians unlike GaySporks, etc), until they become common like nalgene bottles were and then you can either just phase out the disposables or then pass your law with more support, or just let them be as emergency rations for if you lost your spork on the way to taco bell today or whatever and you need another.

Edit: shit, you could even have fast food and fast food+ style places rebrand a spork with their logo and sell them instead of giving away free disposables. Capitalism is the problem and it won't go away? Exploit it against itself and make it work for the enviornment. To some degree it's not only doable but probably easier than force through law.

You get a lot less support with "plastic straws are now illegal, go buy a metal one and some pipe cleaners to carry now" than if you figure out how to make the straws popular with everyone first.