The Church of England is established by law. The Queen is Supreme Governor of the church
Harry needs her permission to get married, not the AoC. The Queen is a deeply religious person. So as I say, I’m sure the couple gave her certain assurances before she gave her blessing
I think you're at crossed wires a little. (Apologies to the Mods, I know this off topic!)
You're absolutely right in what you say. The Church of England is the state church and it has a national role to play both spiritually and in the legislature. The Queen is the Supreme Governor of the Church. But...
The Queen takes no role in the actual governance of the church. That falls to the Archbishop of Canterbury and the General Synod. The Queen's role within the church is two fold: ceremonial and personal. As a private individual, the Queen is a devoted Christian and a regular church go-er. As monarch, she is nominally the head of the church - but she has very little to do with the actual running of the church itself. She rubber stamps decisions, she doesn't actually have any real authority within the set up of the modern Anglican Church.
Prince Harry does require the Queen's permission to announce his intention to marry. It's a little more complex than that but to avoid a huge derail, let's stick with that for now. But the Queen cannot act as celebrant, that is, she has no authority to celebrate a marriage ceremony. That falls to the church and the present rules as laid down by the General Synod state that it is upto the individual parish priest to determine, within both the law and his conscience, as to what requirements he sets for the condition of a couple when they apply to him for permission to marry with his church with him acting as celebrant. If a parish priest refuses to conduct a ceremony for any reason, a couple may petition their local Bishop or apply for a variety of licenses from the Archbishop of Canterbury at the Faculty Office of Lambeth Palace.
Let's say that the Dean of Windsor was asked to perform the ceremony in May. His personal requirements may be that he only considers that either the bride or the groom should be a member of the Anglican church. But the Dean of Windsor isn't being asked to celebrate the marriage. The Archbishop of Canterbury is. The Archbishop must therefore meet with the couple and inquire as to their religious backgrounds. His personal requirements may be that he prefers full communion for both bride and groom, in which case he would have made it clear that he would not,
personally, be able to celebrate the wedding unless Meghan was received into the Anglican Communion. The couple then have a choice. They could ask the Bishop of London. They could ask the Archbishop of York. Or any other cleric permitted to celebrate marriages in Anglican churches. Providing the individual cleric agrees, the Queen doesn't come in it.
The fact is that religion has ceased to be such a high priority in the UK. The Church of England is in decline, to the point where many of it's own senior clergy do not believe it'll last another 20 years. That decline has been in effect for some time and when it comes to the Royal Family, whilst it's absolutely traditional that they are Anglicans and would become such if they were not prior to their marriage, it isn't required. Encouraged in private, perhaps. But not required. If Meghan has taken this decision, it must be because she herself feels she wants to do so. I can assure you that people in Britain aren't bothered about this. If she was Jewish, Hindu, Muslim or Sikh we probably wouldn't raise an eyebrow either (and she could still marry Harry in St George's if that were the case by the way).
Times have changed. Britain is a secular nation with a state church. It's an anomaly that will eventually have to be rectified. The only time anyone has really questioned the role of religion within the Royal Family came with the conversion of the Duchess of Kent to Roman Catholicism in 1994. Even then, people were not concerned about that so much as they were that she may be making a political statement about female ordination. Even when there were rumours that Diana was to convert, it was controversial because of it's legality and not the spiritual connotations.
In short, this isn't an issue. However she came to the decision, whoever encouraged, advised, ordered or demanded, suggested, pleaded, bribed or cajoled her into it, we'll never know. But her religion is a personal matter for her. It's nothing to do with the general public, many of whom haven't stepped foot in a church since their baptisms. It is however very much to do with the Archbishop of Canterbury because in practical terms? It's his church now. Not the Queen's.