What Testers Community offers
Two routes, according to its own site: a free app where developers test each other's apps and earn credits, and paid plans where a managed group of testers covers your 14 days, with a production-access guarantee. If all you need is the opt-in count, fast, it's designed for exactly that.
Where Makers Wall is different
Google's production form asks how engaged your testers were and what you changed because of their feedback. Makers on the wall install your app, use it and send a report with problems and severities. That gives you real answers to write down.
The trade-off is speed of the count: you start with 3 testers per round and can reach 8, so 12 usually means more than one round or a few testers of your own. Earlier testers stay opted in, so the count adds up.





