Is the Roth IRA income limit the same thing as a Roth conversion limit?

No. Direct Roth IRA contributions are subject to income-based limits that depend on filing status and current-year rules. Roth conversions generally are not blocked by the same income threshold.

That does not mean the conversion is tax-free. A high-income taxpayer who makes a nondeductible traditional IRA contribution and converts it may still have a taxable conversion if they own other traditional, SEP, or SIMPLE IRA balances. Separate the eligibility question from the taxable-amount question.