It should not be hard to leverage LSP and DAP. Theia is not opinionated about frontend framework. The basic UI element is a widget which is an HTML element with lifecycle hooks. If your current solution is built with JS tech then it should be possible to embed them in Theia widgets. If no then usually backend can be reused but frontend should be converted.
Here is a presentation from last year TheiaCon about how SAP converted their solution: youtube.com/watch?v=Rj35nCxw_9U You can see there are many approaches.
It should not be hard to leverage LSP and DAP. Theia is not opinionated about frontend framework. The basic UI element is a widget which is an HTML element with lifecycle hooks. If your current solution is built with JS tech then it should be possible to embed them in Theia widgets. If no then usually backend can be reused but frontend should be converted.
Here is a presentation from last year TheiaCon about how SAP converted their solution: youtube.com/watch?v=Rj35nCxw_9U You can see there are many approaches.
Here is on Theia Widget lifecycle: youtube.com/watch?v=T1HDIy7LfFg