Obviously there's an "ad libatum" instruction at the end of this sonata form we've been looking at. Leisner's contribution for the Matiegka Grand Sonata I, 1 was to extend the texture of the coda into a highly arpeggiated embellishment of the opening idea. That's fun, and charming, but there are other options a guitarist and a composer can choose from.
If you were to look at the whole of what Matiegka does with his thematic ideas you might have noticed he did more to play with his modulating transition materials than with his actual themes. Now a more detailed case could be made that his transition still expanded upon ideas in Theme 1, or that were latent in it. We could try to do that some time later, maybe. But something is conspicuously absent in any development, inversion.
This omission might or might not have been intentional. It's impossible to know, but what can be proposed for a guitarist, or a guitarist/composer, when approaching a performance of this kind of music, is to run with this idea--whatever you do in an optional cadenza can be to develop the musical ideas presented in the form in ways that are not actually in the printed work. So in the case of Matiegka we could observe that there weren't really any moments where he took his core thematic idea from Theme 1 and subject it to inversion. This, dear readers, was why we camped out for as long as we did on the simplified form of the theme and what it was. Having done that provided an opportunity to see what didn't get done by Matiegka that we can do here.
So before the "ad libatum" measure, you could insert the following. It'd come after the big half-cadential stopping point you would have already seen in the score. This seems like it would have been more fun to have had at the end of the development had Matiegka not been leaning so hard on using that Mozart quote to get him the kind of recapitulation he wanted but, hey, it's Matiegka's Grand Sonata I, not Wenatchee The Hatchet's. So here's the proposed optional ad libatum cadenza Wenatchee The Hatchet would suggest for this charming sonata form. After the break: