Are edits stable if theme disappears?

Elementary question from a code ignoramus – any advice appreciated.

I started using the wonderful Atahualpa theme almost 20 years ago. Knew nothing of CSS or HTML code, and BytesForAll helpfully did all the heavy lifting. With guidance and examples from forums, I eventually did learn a bit of coding. In total, my WP site must have >100 edits to theme options as provided in menus, plus others I made directly in the various sections. With Atahualpa no longer updated or approved, I worry about losing all that work. So far, everything still seems fine.

Will all of the original Atahualpa-provided code plus my edits and additions survive future WP updates? My site is on a shared server with one of the big hosting companies. There’s nothing interactive there except links; no e-business or anything like that. Except for updating expired links to other sites, I’m rarely updating anything.

If there is a risk, is it practical/affordable to hire someone to redo the existing code to be independent of theme? Other solutions for longevity, aside from uploading everything to archive.org?

Thanks for any advice.