The underscore is used to underline text in Markdown. If you want to display a real underscore like this: _, you have to escape it with a backslash. Some clients apparently interpret this rule even in plain links, and some don’t. If we use real Markdown links this should not happen.
So you have these boards already? Or could you just get other boards with an ESP32 and LiPo charger? Because many already have a printed or ceramic antenna built-in.
Is this not the same ESP32 with an antenna? Although I don’t know how the nRF52840 from your question comes into play here. Don’t you normally use an ESP or an NRF, and not both at the same place (with the exception of a gateway maybe)?