None. For crypto related transactions requiring strict anonymity, I dedicate an old robust Android mobile phone bought specifically, on which LineageOS is installed, which is a custom ROM, security driven, stripped down from Google services sneaking your activity, that can be customized further from raw layer
On top is installed Monerujo, the leading Monero wallet app for Android, which has the service xmr.to integrated into, to support outgoing BTC payments, just in case
With this device, I pay attention to never connect to the internet from home but only on the go via hotspot WiFis, behind double looped VPN, to stay protected from technical failure
I had found a provider of cryptos in the UK, which I had initially met on LocalBitcoins before it required verification. He gave his personal email and address where I could send cash by mail within Europe (cross border). Never been cheated, always was delivered promptly despite several hundreds sent, sometimes above a thousand worth of notes at once (I'd use carbon paper inside an enveloppe to block X-rays - also paid for N this way, except layered inside a book cover for extra insurance)
The premium is then above market price (was 11%) but well worth it to not leave any trail of identification behind and be (almost tbh) entirely confident I can never be traced back. He stopped his money business (illegal activity that normally requires a licence), which is common.
Since then, I'm using a small local IT shop "desk" that legally sells coupons (codes on paper, whose value to retrieve before an expiry date, also cool because it's independant from market fluctuations until claimed), giving as much privacy as the best Bitcoin ATM, not requesting any ID below x hundreds € per week, even cheaper (8% fees).
If you find a way to get XMR (Monero) directly like I did, not involving Bitcoin, not only the obfuscation will be optimised, also not risking manipulation errors, it will really be a lot less of a hassle, without unnecessary trading and transaction (sending over) steps, spread over multiple services online. Personally, I don't get to register on any website, handling away zero documents, and I have only 1 software installed that does it all.
For novices, it mostly requires only the initial accessible setup (if you don't have a computer to install the custom OS via USB, it's something you can pay for at a phone shop, or ask a friend)