Ask HN: Any experience with high risk payment processors

Hi; I am a solo developer running a small online service. Stripe and PayPal are not an option for my use case, so I am considering a high risk payment processor or a high risk merchant account.

If you have used one before, can you share how it went in practice

-How long did onboarding and approval take for you

-What extra documents did they ask for, and how strict was the review

-What fees did you actually pay (setup fees, monthly fees, processing percent, reserves, rolling reserve)

-Did they hold funds often or cause cash flow issues

-Any red flags you wish you knew before signing

Also, if you think this is a bad plan for a solo dev, what would you do instead

If you can recommend a few providers you trust, that would help a lot. Thanks