Laos is starting eVisa now so you would have to apply online and they state 10-15 days processing time. a long time… probably better to fly to vietnam and do it online (evisa) there. takes maybe 5 days. have all documents prepared. some embassies require 3 or 6 months of financial proof / bank statements… you should search this group for the specific embassy to learn about the requirements
1. you need to leave the country to apply. everything else would be illegal and sketchy
2. all the countries are changing to eVisa and there is no more 1day visa run to Laos for example. Laos especially lists 10-15 days processing time with the eVisa starting from january (all appointments booked our weeks ago for 2024).
3. an agency cannot really impact your visa process. they can check your documents and help with questions. but so can this fb group for free. up to you if you want to pay that much money for basicaly 20mins of work - uploading 4 documents.