Hello @DryChips,
It depends on how source list is set up. If all data is stored in one list, you can try the approach using Extra fields, described in this post:
If data is stored in multiple lists, use PnPjs function to get field values:
fd.field('Field1').$on('change', function(value){
pnp.sp.web.lists.getByTitle('List').items.getById(value.ID).get().then(function(item){
fd.field('Title').value = item.Title
});
});