Yes, you can activate the eSIM-enabled tablet with your existing mobile plan via eSIM and then use both the mobile and the tablet. The tablet supports eSIM and you can activate the eSIM via the "SIM Manager" menu in the settings. You can manage multiple SIM profiles and switch between them.

It is important that your mobile phone provider allows you to use a plan on several devices with eSIM at the same time. Activation is usually done by scanning a QR code that you receive from your supplier or by manually entering the eSIM data. After activation, you can select which device is currently using the mobile connection in the SIM Manager.

Please note that the device should not be restarted during the eSIM installation to avoid errors. If you have problems, activation directly via the SIM Manager instead of via a third-party app often helps.

In short: Your existing mobile plan can be activated on the tablet via eSIM and you can then use both devices with the same plan, provided your supplier supports this.