Step 1: Use https://bisq.network to convert your tainted BTC to some privacy coin. Do it in parts, probably 1 BTC at a time and trade with a different user for each transaction.
Step 2: Convert those privacy coins to BTC again through some instant crypto exchange, e.g. https://coinswitch.co. Use Tor.
Now, you have coins from exchanges itself. Any exchange will gladly accept it.
p.s. Before choosing privacy coins for conversion, make sure that those coins are convertible through your chosen instant crypto exchange. In general, Dash & Monero are widely available.