Yes, yes you can.
Yesterday we went up Cadair Idris, the second tallest mountain in Wales. Very slowly. This involved 700m of ascent, and (for me) a 3-scoop Huel breakfast, two bananas, an apple, and a 3-scoop Huel lunch at the summit.
At the moment I’m having one food meal a day (the rest Huel) and I can tell you that last night post-hike I was pretty hungry . We went out for a Greek meal and I ate a massive salad and all the bread. Today has also been a pretty hungry day with an extra scoop of Huel mid afternoon, and masses of sweet potato wedges for tea. I’d have been hungry after climbing a mountain even if I’d been eating protein bars and nuts all the way up, though, so I don’t think Huel has come out too badly here.