The most useful number you can get is from your own stack: put your actual app on the box and hit it with k6 or wrk using a realistic mix of pages, and watch memory rather than CPU. On 2 GB the failure mode is almost always RAM: too many PHP-FPM/worker processes plus a database on default buffers, then swap thrashing and the OOM killer, long before the single core is the limit.

What buys the most headroom on boxes this size:

• cap the worker count (pm.max_children or the equivalent) to what actually fits in RAM
• size the DB buffer pool deliberately instead of leaving defaults
• zram for bursts
• serve anything static or cacheable straight from nginx so it never touches the app

And rate-limit or block the obvious scrapers. As someone said above, bot traffic is often the real load.