PLEASE HELP! Hamster has big lump on foot

[souffle]

Don't even think about it. How do you know that little skin junction may not contain a large blood vessel or major nerve and he will bleed to death? You also don't have access to painkillers over the counter suitable for hamsters.
It may become critical at some point and start to bleed anyway but that will be nature taking its course then.
When we take on an animal we make a promise to get that animal vet care should it need it. Is there a charity anywhere that provide vet care or a rescue centre? I know how hard this is but if he seems pain free and you simply cannot have it seen then the only option is to remove anything that he may damage it on like the wheel and provide alternative enrichment. Start saving now in case things become critical and look for a charity that may be able to help. Please do not propose home surgery as nobody on this forum will support you on this.