merge two ParamMap angular

I have the following code that works fine:

let urlParameters = combineLatest(
  [this.route.params, this.route.queryParams], (params, queryParams) => ({
      ...params, ...queryParams
}));

urlParameters.subscribe(params => {
  console.log(params["type"]);
});

in the result I have new object and can access as params["type"]

but can I do the same with queryParamMap and paramMap? like:

let urlParameters = combineLatest(
  [this.route.paramMap, this.route.queryParamMap], (params, queryParams) => ([
    ...params, ...queryParams
]));

urlParameters.subscribe(params => {
  console.log(params.get("type"));
});

and I can use ParamMap methods like params.get("type")

First access the keys using paramMap.keys, then loop these values and store them in a temporary object finalParams (do this for all map value you want to merge, here it is paramMap and queryParamMap), then we can use convertToParamMap from @angular/router to convert it to param map, with both the merged values.

The paramMap is a custom class ParamMap - Source Code and not the default Javascript map, hence, we need to recreate it with the respective properties to merge them.

import { Component } from '@angular/core';
import { ParamMap } from '@angular/router';
import { convertToParamMap } from '@angular/router';
import { ActivatedRoute } from '@angular/router';
import { combineLatest } from 'rxjs';
import { map } from 'rxjs/operators';

@Component({
  selector: 'ngc-child',
  template: 'Child:<p>Param: {{params.id}}</p>',
})
export class ChildComponent {
  params: any;

  constructor(route: ActivatedRoute) {
    let urlParameters = combineLatest([
      route.paramMap,
      route.queryParamMap,
    ]).pipe(
      map(([paramMap, queryParamMap]) => {
        const finalParams = {};
        this.mapParams(paramMap, finalParams);
        this.mapParams(queryParamMap, finalParams);
        return convertToParamMap(finalParams);
      })
    );

    urlParameters.subscribe((result) => {
      console.log(result.get('id'));
      console.log(result.get('test'));
    });
  }

  mapParams(paramMap, finalParams) {
    const keys = paramMap.keys;
    keys.forEach((key: string) => {
      const allParams = paramMap.getAll(key);
      finalParams[key] = allParams?.length <= 1 ? paramMap.get(key) : allParams;
    });
  }
}

Stackblitz Demo