A Bible that includes the US Pledge of Allegiance and the US Constitution is pretty much a 1950's-era conservative meme. This is likely why the Bible that Trump endorsed was created in the first place. Neither Trump or the Bible printing company originated the concept of merging US Constitution studies and Bible studies - that is an old 1950's Americana thing.
The claims that this requirement is anti-competitive are weak, even if Trump is the only person currently selling that Bible and gave schools the idea for the concept. None of it is copyrighted, and none of it is original. For it to be anti-competitive would have to play dumb and pretend that this is hard to obtain or create, or that no publishing companies have ever produced special prints for schools, which is false.
If someone who is eligible to make a bid wants to create that meme Bible, they can throw it together and order prints within a day with various online services. Any major publishing house has the resources to bid for the requirements easily. The God Bless the USA Bible that Trump endorsed is also $60. If someone can beat that price in a government bid, they get the contract.
Except thats not how it works.
I've done the whole bidding process.
So first you get a list of approved suppliers from the state. This is done annually or bi-annually and doesn't change much.
The suppliers have pre-agreed upon prices for items. This is a contract and can't be changed.
If no approved suppliers has the item you need on their lists, you are allowed to find one who does. And lo and behold... They did.
A publisher can't simply go "we'll make you one to order" as that won't be on the list.
It's VERY possible that the mandate was made after the list was published and the publishing company Trump uses added his bible to the contract list. Which makes it the default winner. But I'd need to see timelines.