If you already use to Nikon, just get Zfc.
Unless your Nikon lenses are with your relatives, then get the Sony A6700 with 18-135mm. This is more than enough for your travel. Don't really need a DSLR nowadays as it's just way too heavy to lug around. Unless you are a serious hobbyist and need high quality photos, then full frame mirrorless camera is the way to go. DSLR will be phase out very soon, so don't head that direction.
I have D70, D810, D4s.....all sitting in the dry cabinet. Now I use Z7ii with Z6ii as back up most of my time.
Get Sony A series if you love editing videos and creating video contents. If you are just looking for still images, any mirrorless cam is good enough. Although Fujifilm are not full frame but their APS-C sensors are pretty good and one of the best in the market, especially the X Series.
Best to go down to Funan and have a feel on all the cameras that is available at TK Foto (I am not related to them but they have it on display which you can test test and have a feel). You don't really need a high end ones. A Fujifilm XT-30 is more than sufficient but limited stock. You can also try the X-S20.