Hiring an accountant to help build a modern accounting SaaS

We're building an accounting software. Looking for an accountant who can spec the accounting logic (double-entry, VAT, multi-currency, reports), review the product against real scenarios, and work directly with our two devs to translate requirements into features.
Ideal if you've worked at or with an accounting SaaS (Xero, QuickBooks, Sage, Akaunting) or done consulting for fintech. EU VAT experience is a big plus.
Remote, part time to full time, long-term.. Pay negotiable.