Is it possible to get the hex data from a transaction id which i haven't personally signed, and which is currently not being broadcasted by any nodes/isn't in the mempool.
Meaning that i only have the standard transaction id to work with. ( Something like 9021b49d445c719106c95d561b9c3fac7bcb3650db67684a9226cd7fa1e1c1a0, but then unbroadcasted, and unconfirmed/not in the mempool, in which case the links you provided about btc.com and blockchain.info's resolver won't work.).
(Since i would need the hex encoded data to push a transaction back into the mempool, right? Would that be possible with only an old valid transaction id that i have?) I don't think so.
it's only possible if the tx has been broadcasted at least once and reached
bitaps or btc.com
bitaps is the explorer I know which keeps track all transactions: unconfirmed, double spend, dropped txs
bitaps openly shows all related txs on the address page, but btc.com only list confirmed and valid mempool txs
on btc.com you have to know the exact txid to be able to see other transaction data
if it never reached these 2 explorers and dropped, most likely you cannot get the hex by means of knowing its txid only
there might be other explorers, but I only use these two to query txid if it doesn't exist on bc.info anymore
edit: I'm sorry I typed extra 'p' on the url, corrected the url to
https://bitaps.com/@AdolfinWolf please edit your post too if you can, so people won't be directed to wrong site