If you wanted to import via the API it can be done, though with your number of products it will still take a while, but you will have more insight into where you are and can probably pause the job without any repercussions.
If you were to make Product creation API requests that includes the variant information in them (assuming 3 variants per product) and using a default API limit (refresh of 2 requests per second, or 2 concurrent requests) you could probably finish creating all those products in about 67 minutes.