No problem at all – timber frame walls are structurally load bearing so you’ll face no issue hanging the likes of a TV or photo frame. If you’re concerned about needing to attach directly to a stud, that’s actually no longer the case. Timber frame houses are dry lined with plasterboard and often internally insulated (achieving a Passive Standard u-value). So it’s actually the plasterboard that the the item would be mounted to. This would be the same in a block house with a dry lined or internally insulated wall. Plasterboard fixings are sold in every local hardware shop and can take well over 100kg of weight. The brand “Grip It” is an example of an extremely strong fixing. These are capable of hanging large TV’s, kitchen cabinets, heavy curtains and even radiators!
And consider this – if you were to follow an air tightness process for your block build and go to hang a TV on your internal block wall, you’re essentially penetrating your air tightness membrane!