Laravel push notification client selection problem

The requirements are as follows:
1. The company's HRMS needs push notifications, but due to various reasons, the server cannot be exposed to the public network!
2. It is best to be free and have a good ecosystem (other microservices can be integrated in the future)
3. Have multi-platform clients

Because of the first one, the WeChat official account cannot be implemented!

I took a look at BearyChat’s Incoming bot, and it seems that it can only be pushed to discussion groups, not individuals!
But his other ecosystems are doing very well, so I want to know if there are any similar platforms!

Reply content:

The requirements are as follows:
1. The company's HRMS needs push notifications, but due to various reasons, the server cannot be exposed to the public network!
2. It is best to be free and have a good ecosystem (other microservices can be integrated in the future)
3. Have multi-platform clients

Because of the first one, the WeChat official account cannot be implemented!

I took a look at BearyChat’s Incoming bot, and it seems that it can only be pushed to discussion groups, not individuals!
But his other ecosystems are doing very well, so I want to know if there are any similar platforms!