I've been using ts-prune[1] for years at this point. The project is in maintenance mode but works fine so I've kept using it. I've been looking into Knip[2] which is recommended by the authors of ts-prune though it's been slow mostly because there's little incentive with the current tool working fine.
I was in a similar spot, but knip offers more information that ts-prune, and ts-prune may trip on some newer TS syntax. I've been happy using knip so far.
[1]: https://github.com/nadeesha/ts-prune
[2]: https://github.com/webpro-nl/knip