Being one of the lucky few to get my Steam Frame a few weeks ago, I have been using it quite a bit since then. I have been buying some third-party accessories to mitigate some of its weaknesses.
First the obvious one: it is surprisingly light and small, but overall not comfortable enough due to my glasses. To solve that I went ahead and bought prescription lenses from VR Optician (119€ including fast shipping and additional prescription fee).
Then I figured I had better protect it against sunlight because I do not have one of those fancy head mounts nor do I want to pack it in its box between each use. Thus I got an AMVR lens cover that fits quite well (13€).
And finally the battery life situation is... Well it's bad. I got decent VR legs and can play for hours, but the battery only lasts at most 1h30 when running PCVR at 120Hz. So I got myself a UGREEN Nexode 145W 25000mAh Power Bank (56€), 2 short angled USB-C cables (24€), round magnetic USB-C adapters (16€) and a small fanny pack (10€).
I will also say there has been some trial and error regarding the magnetic adapter. The idea is to protect the headset port in case the cable snags on anything. I wanted to plug it directly in the headset port, but it tends to disconnect when I turn my head. The tradeoff I landed on is : one very short cable plugged in, magnetically coupled with a longer one that goes to the battery. The 240W-rated USB-C cables are also overkill but hey, not that much of a price difference (they are quite thick though and contributed some in my disconnect issue).
So there you have it, 238€ on top of the initial Steam Frame + ergonomic accessories kit purchase (which is a must-have if you ask me), not counting said trial and error.
Update: there are strong arguments in comments against using magnetic adapters. I'll be ditching that and keeping the 2 cables approach so that there is a straight connection (hopefully weaker than the angled plugs) that can unplug more easily than the battery or headset side if the cable snags on something.
Mrs. Noodle just got smaller frames with her new prescription so they'd fit better in the Steam Frame. And a long enough USB-C cable can let you plug in to the wall for indefinite play.
Lucky for her it was time to renew ! I would wager changing glasses to fit the Frame would be a lot more costly than the inserts for most people. In my opinion, using the Frame as a wired device kind of defeats its whole purpose (except for seated games). One might as well get a second-hand HP Reverb G2 or something like that for a fraction of the cost if it's to play wired.