Hi @datlehehe, welcome to the discourse!
If you are interested in contributing to the Linear algebra and sparse matrices (stdlib) project, take a look here GSoC 2024 Contributor Instructions · fortran-lang/webpage Wiki · GitHub regarding the application process. Pay close attention to the bullet points number 4 and 5 taking into account the application deadline April 2- 18:00 UTC
Within the description of the project you’ll find some useful discussions under “related issue” and “WIP implementations”. Once you have taken a look, feel free to continue a discussion here for your first PR. Two key points that you’ll see in the links are: the non-OOP basic kernels for sparse matrices and the OOP types for data containment. Both aspects would then help push through interfacing a higher-level API for sparse matrices which should maintain some coherence with the current effort by @FedericoPerini to wrap BLAS/LAPACK