I use an older 32-bit Intel Pentium Computer which is not getting any microcode updates. Anyway the PC is working just fine and I want to protect it against spectre/meltdown vulnerabilities. Is there any Linux distribution providing patches? As I know from the Ubuntu wiki-page only Spectre Variant 1 is addressed by the Ubuntu team.
On 32-bit x86, both Spectre variants are fixed, including in Ubuntu. Fixes for Meltdown are still being worked on; as far as I know, no distribution is shipping them, although I haven’t checked openSUSE (the patches are being developed by SUSE so they might show up there earlier).