Might be overkill (or underkill), but Tiny Core Linux is the most lightweight I know. While having an up to date kernel (6.1.2) and glibc (2.3.6).
What are the minimum requirements? An absolute minimum of RAM is 46mb. TC won’t boot with anything less, no matter how many terabytes of swap you have. Microcore runs with 28mb of ram. The minimum cpu is i486DX (486 with a math processor). A recommended configuration: Pentium 2 or better, 128mb of ram + some swap