You can't deposit funds to go above 100k, yes. You can still get zapped by others on SN to go above 100k though. The limit is only about deposits. We will show this in the wallet page if you're above the limit:
Your wallet is over the current limit (100k sats) Deposits to your wallet from outside of SN are blocked. Please spend or withdraw sats to restore full wallet functionality.
With an attached wallet, these limits still apply to your custodial wallet but if you don't have enough funds in your custodial wallet (because of the limits for example), we'll try your attached wallet.