I agree with Mark about the performance of the Diamond RH-770 - I frequently get good reports using it and it’s my first-choice 2m SOTA antenna too. However, it is mechanically a bit fragile (I’ve often read that the cheap 770 clones are even more fragile).
So, if you take Phil’s (good) advice and get yourself a H/T, I wouldn’t use the two (directly connected) together whilst ‘pedestrian’ (if by that term you mean walking about). My H/T has a SMA socket and the 770 sways about in high winds putting stress on the SMA so I use it only at the summit. So use whilst walking is bound to increase the risk of problems later.
There’s always the risk of tripping and damaging both while walking. Maybe a flexible coax patch lead would help if you mount the telescopic antenna to your rucksack.