Why would you migrate to another version? I would suggest to just update the existing version to 2.4.5. Or, if you are on a live website first create a clone of the 2.4.2 including database and upgrade from there. If you insist on migrating, we use the Firebear improved import/export extension for our imports and exports. It's a useful extension for a lot of jobs. As said, I would go for the first option (just update the existing installation).
You might want as solution like Firebear because you might find it useful for other tasks as well. In that case it might be a good investment. I heard several customers in the past using paid services without any real succes-story there. I would limit your expectations there. Especially for harder projects like yours. Also for 'an expert' it might take a lot of time. I have done quite a few migrations myself (also from 1.9 to 2.4.5) and it's never a easy process because of all extensions.
In general I would advise you to use your existing install, because it already contains all products, orders and customers. Export them and start from there. Make sure your new install has the proper attributes available. If this does not work, the data might be so bad that also other forms of import/export or migration would not work. In both cases the existing data should be ok to get this working.