Th application has, in the settings the possibility to configure the node, you install the node in a PC and once configured and fully loaded, you can point the mobile app to your node. You need to learn about it, the easiest way is with Umbrel OS, https://umbrel.com/, but if you are going down that rabbit hole, I will rather recommend you https://start9.com/, way more stable and a bit more expensive, but the maintenance will be minimum and will be quite stable.

If you decide to go with Umbrel because the low cost, I will suggest you do not install any application but the Bitcoin Node, Electrum Server and if you use Samourai, the Samourai DOJO server, nothing more, this will improve the stability of the OS...