Several gases are water soluble, like HCl, and some of the NOx gases...
Bubbling the gases through a cold water trap can capture some of these, they can also bubble through so fast you will not capture them all, what may help to capture a little more is, if you make them go through this trap as smaller gas bubbles, maybe you can take the tube from the filter vessel and melt the end of the hose that will go down into the water of the water trap vessel, and punch many small holes in the side of this tube with a hot needle, towards the bottom of the closed tube, or use a large air stone type bubbler so that the gases will have to pass through these small holes to create smaller bubbles to bubble up through the cold (ice) water, where more gas to water contact can help to .capture more of the gases flowing through the solution.
You may also need more than one trap.
The exit tube from the water trap (taking gases from the top of this trap can go into another bubbler vessel.
Example, Hydrogen chloride gases will dissolve in cold water to form a solution of hydrochloric acid.
HCl (g) + H2O --> HCl acid
Nitrogen dioxide gases NO2, will dissolve in cold water to form a solution of nitric acid.
NO2 + H2O --> HNO3
NO (nitric oxide) is one of the gases that is not water soluble, this clear gas can be converted to NO2 with oxygen (since this is in a vacuum stream introducing oxygen to the vessel, or system would lower your vacuum capability), an alternative would be to add the oxygen to the water using hydrogen peroxide.
NO (g) +O2 --> NO2 (g)
Then
NO2 (g) + H2O à HNO3
Or
NO (g) + H2O2 à HNO3
Depending on what gases you are trying to capture, you can try and use a solution to help neutralize the gases, so to help to convert the gas to a more soluble form, this can be the scrubber vessel before the gases go to the inlet of your vacuum pump.
Example, acidic gases like HCl you can neutralize with a substance of dissolved sodium hydroxide to help to convert the gas to a soluble solution of NaCl salt water.
HCl (g) + NaOH --> NaCl + H2O
Some of the NOx gases can also be converted to nitrate salts, in the sodium hydroxide solution, which could help to keep them dissolved in solution as sodium nitrate.
Sodium hydroxide is not the only base that can be used in the scrubber, but it is one of the stronger solutions.
Glassware can be etched by strong hydroxide solutions, so you may not want to use your nice lab ware, you can always use old lab ware or other types of old bottles, with corks drilled out for the hoses.
The taller the bottles the further the gases will have to travel to bubble up out of the solution.
I really do not believe the refrigeration pump would survive long but you can try it.
There can be several ways to create a vacuum, even without the use of mechanical vacuum pump, some f which you could make with a few odds and ends, like the 55 gallon barrel of water sitting on a stand, or on top of another barrel, with he vacuum tube coming off the top of the sealed drum, and a drain valve to drain the water, to create the vacuum it the top of your drum this water could be drained into a lower barrel, (two barrels one sitting on the other with boards between them and piping and valve between the two barrels), a small pump can be set up t return the water to the upper barrel later, many different ways of getting a vacuum have been discussed several times on the forum, One I am have thought about is take a plastic air pump (for airing up tires or tubes), or one of those river raft foot pumps (which would need a spring return, and change the valve operation (check valves) to make it into a vacuum pump.
I have several types of vacuum pumps (for different purposes) but I also like to tinker and build things, so I may build some things just to have some fun tinkering, even if they do not always work, it can be a fun way to learn some things, and its even more fun when it works as intended.