Have to agree with others here
@Ke**
, it is not necessary wheelchair friendly, but it does depend also on how dependent the person is with a wheelchair, and where you intend to go.
I pushed guests (I work here Thailand in travel) around Thailand, Cambodia, Laos and Vietnam a few years back, when it was much more difficult than now. So it is possible but not advised.
Something to also know which maybe helpful for travellers here. You can hire wheelchairs from private hospitals if necessary across SE Asia or buy them fairly cheaply and sell or donate them to hospitals before you leave, if you need them due to an accident or don’t want to bring one from home.