I also have been building a spreadsheet with all of the kanji introduced in the MNN vocab lessons matched up with their WK level. Her videos were especially helpful for explaining the て-form to me, months before I got there in MNN, haha! Japanese Ammo with Misa is my favorite grammar resource so far because her explanations are really clear and in-depth, and she talks about natural usage in addition to more formal language. Some of the grammar explanations in MNN can be a little confusing, especially the verb forms, so if you get stuck, I recommend looking up the same grammar point somewhere else. If you do this, the book becomes much easier to just sit and read with near 100% comprehension, since you only have to worry about figuring out the grammar and not trying to struggle with new grammar and unknown vocab at the same time.

If SRS works well for you, Anki is a great program to use for this, since it’s free and infinitely customizable. The most important advice I can give is to learn the vocab before attempting to read the lesson. That remains my main strategy for proceeding through the textbook. Thanks for finding and linking my previous post, I still stand by all of the advice I gave there. I am currently using Minna no Nihongo, yes! I’m finishing up lesson 17 (out of 50) currently, and I’ve been using the textbook since I believe March, and have already been able to apply the stuff I’m learning in the book to reading manga and other Japanese in native media, so it’s definitely possible to successfully use it for self-study, I think.

Minna no nihongo 2 answer key