The Elk Mastodon client is my preferred frontend, written in Nuxt. It has support for deploying seamlessly on Vercel but it needs access to a caching database. By default it expects Cloudflare but it also supports Vercel KV (Redis) which is included in Vercel's free tier (hobby plan).
You will need to activate Vercel KV, start a db project and and get the KV_REST_API_URL and KV_REST_API_TOKEN values it provides. Then set these values for your deployment env.
NUXT_STORAGE_DRIVER=vercel
KV_REST_API_URL=...
KV_REST_API_TOKEN=...