Your have to understand, that TTL (through the lens) metering was not developed until the Pentax Spotmatic in 1960 and a few more years later before production models started hitting the market. Before then, everyone was adding some form of ungainly looking meter.
Pentax was the first manufacturer to show a prototype behind-the-lens metering SLR camera, which was named the Pentax Spotmatic. The camera was shown at the 1960 Photokina show. However, the Topcon RE Super was the first SLR commercially offered with TTL metering, first offered in 1963, and the camera was quite compact. This is a photo of a Beseler marketed version of the RE Super, offered in the USA as the Beseler Topcon Super D.
The Pentax Spotmatic, even more compact and lighter than the RE Super, was first offered in 1964.
The Nikon F body was first launched in 1959, and was about the same size as the Topcon RE Super body, but while the RE Super had all of its metering designed into the body, the Nikon F needed to use a supplementary finder to add metering to a totally mechanical camera body, with all of the electronics and battery and mechanical linkage to the lens diaphram control ring, hence the bulk of the Photomic finder. The first Photomic was launched in 1962 and offered a meter that was
not TTL, but then the Photomic T was launched in 1965 to offer TTL metering.