Always have a decoy wallet, in this wallet you must reserve a amount that you are willing to lose (something like US$3 ~ 50) when testing a new wallet just downloaded, you enter this test decoy seedphrase, after all, these fake wallets usually have a malicious code to drain wallets immediately as soon as a wallet with amount is imported, so if your decoy wallet is drained, you will know right away that it is a scam wallet.
Should we use our funds to test for fake or malicious wallet? The points you stated above may be right to some extent but to be frank, you have to make sure you are downloading these wallets apps from the right source, which everyone knows as their official web. Play store, can no longer be trusted so even if you are downloading from Google Play store or other official stores, you should make sure that the website redirects you there. Don't click unknown links to download so as to avoid downloading Trojans or malicious apps.
This way, you don't have to test the authenticity of the wallet with your funds or having to try a decoy just as you stated in your op.
Obviously for someone with experience it sounds unnecessary, but most people don't even understand why an App is in the store, so for the average user, they only know how to go to their app store and download. What is clear is that if you download an App to store money you should follow a security guide. Any Wallet, even a HW, can be compromised. If you use trust as a basis for downloading any software, you are making the first mistake, even if you download a wallet from the same website and follow any of the steps mentioned. Then, testing a wallet with $100 does not offend my knowledge, it strengthens my distrust.