Hi Joseph,
It's awesome to feel thrilled and excited about learning foundations and basics - I always notice that when these things feel like a fun game, it doesn't feel like learning "basics" to me anymore, because playing these notes is the only important thing in the world. This feeling is awesome but only while it is there, and the fun games feeling is certainly not always there for me every day.
My biggest piece of advice is to be patient, and try to accept each day's practice and progress for what it is in itself. Note: I am not always great at taking my own advice. This is really, really hard to do.
A strategy I used while building finger strength is to play chromatic scales for a few minutes per day. I found this to be an easy way to get some extra notes in each day and get my fingers used to playing more frequently. Starting on the lowest string, I would just play the frets 1234 and then go up a string, then come back down when I reached the top. Feel free to go up and down the fretboard wherever you'd like, or try variations of the fret sequence so that it is not always the same. Skipping notes from 1324 / 4231 is a very good pattern for building dexterity.
Also, Tomo has a video on YouTube that details some of his warm-up exercises. I have been doing these nearly every day for the past few weeks and it makes a big difference! My favorite of these exercises is the first he shows, which is a version of what I listed above.
The pattern goes 1212 3212 3432 1234 while going up the fretboard, then in reverse 4343 2343 2123 4321 on the way down.
As for switching triads / chords, that is something that still gives me some trouble. Again, patience is key, but that is not a satisfying answer to hear.
There is another online guitar instructor that I saw give advice on learning to change chords. He suggested picking two chords that you are learning to switch between. In this case, it would be your root and inverted triads. Set a timer for one minute and play those chords, changing between them as smoothly as you possibly can. Don't focus on speed for now, just keep it smooth. Count how many times you can switch between them during one minute. See if you can beat your high score next time!
The burnout feeling is difficult to get through sometimes. Are there any songs that you have in mind to start learning? Maybe try learning a riff or lick from that tune. See if you can figure it out yourself by ear - I always get the biggest thrill from learning a song on my own! But if you decide to use sheet music, or a tab, that's fine too! Honestly I think that learning even with these methods requires a decent amount of "playing by ear" to figure things out.
It sounds to me like the fear of memorizing shapes /tabs is becoming a blocker to having fun while learning. Shapes and tabs are tools, and we are all still allowed to use them from time to time if it helps us along the journey. :D
And besides, if you "accidentally memorize" a shape it's not going to hurt you! Having a shape in mind is not the problem - the problem is a reliance on learning only the shapes, while ignoring the notes. Just keep that in mind the next time you're practicing, and when you notice yourself playing that shape maybe slow down and try to think of the exact notes / degrees rather than the shapes or fret numbers. This has helped me big time. Heck, Tomo has a video up on YouTube about the CAGED system and how those specific shapes are great to get someone started with analyzing where the notes are and learning the fretboard.
EDIT: I'm not sure if these two YouTube videos are also covered here in Guitar Wisdom. I just signed up for GW this week, and I recall seeing these two videos before I subscribed.