I am also a solo freelancer with simplified bookkeeping.
I experienced that Double-entry bookkeeping is - beyond the initial learning curve - not more effort than simple book keeping. That is because it automatically avoids common errors. GnuCash works fine for me since 20 years. Never looking back to fragile spreadsheets and half-baken Access DB's.
How is the GnuCash DB any different from using an Access DB?
For simplified bookkeeping GnuCash, and most generalized bookkeeping programs, is overkill.
I accomplish the same thing with 250 lines of Python, and the result is that I get exactly the numbers I need to enter into Skatteverkets e-tjänst, and nothing else. And each transaction is one yaml file, and stored off-site with git.
Double entry bookkeeping is the gold standard in finance bookkeeping since the romans.
It is not overkill, because once mastered it is very easy to handle especially with a program that implements the logic like GnuCash. The problem for novices is usually to understand the logic: https://gnucash-docs-rst.readthedocs.io/en/latest/guide/C/ch...
