Successful independence movements this early could require multiple PODs in the 19th century. Decolonization happened in India when it did because an earlier Anglo-phile elite that pushed for equal rights with the Empire's white subjects had been exhausted/discredited, and there was a substantial university-educated elite that had brought home European ideas about nationalism.
By the '20s and '30s, the Russo-Japanese war and Italo-Ethiopian wars had broken the initial cracks in the idea of white military supremacy, but struggling for independence (military or otherwise) was still hard to imagine without the humiliating Japanese defeats of the Europeans in SE Asia, and the exhaustion of Britain and France.
The Democratic Republic of Congo experienced the horrendous post-independence history that it did OTL because a country of 15 million people had about 15 people with a college education. India experienced a relatively stable history after independence because there was a well-developed Indian civil service available to continue running the country after independence, and the Congress party believed in the rule of law. Nehruvian socialism and the license Raj may have held back economic development for decades, but at least Nehru and his successors believed in democracy.
Independence in the '20s or '30s would probably leave most new states looking more like the DRC than India. It depends on how far-sighted the late empires are. Ghana didn't gain independence until 1957, but constitutional reforms in 1946 and 1951 allowed Ghanians to practice electing representatives, and set up a proto-parliament that could evolve into a fully fledged state. If there is a an educated elite available to run the country and a transitional period where elections are held and prototypes of state institutions are established, then the new countries will do well. If not, there will be chaos.
Decolonization during the interwar period would make world politics interesting. Stalin would probably send weapons and advisors to set up socialist states, and the fascist powers would see the new countries as an easy territorial conquest. Mussolini might declare his new Roman Empire after the conquest of Tunisia rather than Ethiopia. The colonial powers would likely practice a more exaggerated version of Franceafrique if the development gap between ex-colonies and the metropole is larger.
The new post-colonial states in Southeast Asia may sign basing agreements with Japan members of the Co-Prosperity with various degrees of de-facto and de jure independence. This depends on whether or not the colonizers leave behind military bases, 99 year leases or treaty ports like Hong Kong, Macau, or the former US military base at Subic Bay in the Philippines.